@HAWK is right-- true leaders prefer to be acknowledged by their peers rather than self-declared. That said, I'll do what I can to answer your questions.
1) My thoughts:
i.) The web design industry, as a whole, does not have a good understanding of the difference and value propositions focusing on both user interface and user experience. While the two are often related, they are also often confused. Muddying the waters is the fact that many professionals in our industry are asked to perform a variety of functions that, ideally, would either be performed by both a UI and a UX professional. The crossover is negating some of the gains of having two separate teams focusing on different elements of each. To get a feel for the difference and why it's important, please feel free to check out my blog post on the subject. Educating young professionals and corporate leadership on the difference is one way I work to negate the impact of this issue.
ii.) Many professionals come to the UX industry from a wide variety of backgrounds and experiences. In truth, you don't have to be a good technology professional to be a good UX'er-- you need to have a passion for solving problems, a drive for improvement, and the ability and empathy to see things from your users' perspectives. As a result, UX professionals come from a variety of backgrounds. Here on UX Mastery, we have architects, engineers, journalists, and a variety of other professionals.
This is both a strength of the industry, as it means we have a wide variety of valuable and interesting skill sets to draw from, but it's also a detriment in that many look to get into the UX industry without having a common skill set. Furthermore, the skill set employers ask for is often at odds with the value of the skills of a potential employee could offer.
Defining that skill set and working to create a common conception of what basic skills a UX'er should possess before getting into different areas of the business is one of the reasons I'm here on UX Mastery. I personally had careers as a sports journalist, freelance web developer, digital sign developer, restaurant server, retail manager, call center phone jockey, and corporate trainer before I finally settled into this career. Each job taught me something valuable to my UX career, and I feel that I have a lot to offer the community at large. I'm here on UX Mastery offering my experience and thoughts in every way possible to try and lessen the impact of gaps in knowledge or experience within the community.
iii.) The wide variety of technology requiring UX focus, along with the variety of different roles a UX'er might pursue, make finding a niche difficult for many people. Simply put, there's a lot of opportunities out there in the UX world at the moment. Different people might be more well-suited to different careers at different points in time.
As an example, I'm currently mentoring a really great young professional who's trying to get his foot into the UX world. His background is in the financial world, where he interacts with customers and provides technical support on a daily basis. Due to his relative newness to the industry, his affinity for statistics, and his excellent people skills, I'm guiding him towards exploring a career as a UX Researcher, a career very different from a UX Designer or Engineer role.
By providing online and in-person mentoring, I'm doing what I can to help new professionals build their skills and find their niche. My hope is this will, in some small way, help to eliminate this barrier to entry for many who would be well-suited to the UX world.
2.) Being successful and being a leader are two very different things. Some of the most successful people I know are people who merely follow orders to a T, providing excellent execution of the ideas and thoughts of others. There's absolutely nothing wrong with this. I merely use it as an example of how the two aren't necessarily correlated.
To be successful, I'd recommend anyone looking to get into the world of UX do three things-- build the basic skills required of every UX professional, find a niche within the industry to focus on, and to find ways to get practical, real-world experience.
I talk a bit about the first two points in my answer to your first question, but when it comes to building real-world experience it can often be difficult to find opportunities to which you can contribute. @seyonwind, perhaps, can provide some insight into some ways to get some good experience ahead of trying to enter the industry full-time as his work ethic and diligence in volunteering for UX-related projects and causes is apparent to all who know him, online or not. My advice is to work on your own projects, to volunteer for open source projects, or offer your skills to charity (catchafire.org/ is a great place to start.)
To be a leader, it's imperative that you seek to serve the industry in any way you can. For different people, that means different things. For me, it means hanging out in places like this and answering questions for the interested and inquisitive individuals like you. For others, it takes the shape of volunteering their services to nonprofits, blogging on the subject of UX, and providing mentoring services for young professionals.
3.) Who knows where UX growth will come from in the next 3-5 years? One of my favorite areas that hasn't had much discussion, but will need a lot of UX attention, will be in self-driving cars and related applications. Tesla right now is leading the world in this area, but major and minor players alike will create quite a bit of competition as they enter the industry. That means more specific UX jobs for the industry.
4.) In general, corporate leadership will need the ability to better understand the value proposition of investing in user experience. At the moment, it feels like a bit of a reaction to buzzwords rather than true understanding of the UX professional and their value that's driving the UX industry.
I hope that helps! Apologies for any typos-- I'm hammering this out before a meeting and not giving it my usual once-over before I post as said meeting starts in just a minute or two. Let me know if I can clarify anything or provide any additional context