I am a big believer in humen ingenuity and the ability of mankind to continue to explore and "reach for the stars." Those small points of light that have hovered above our heads since the dawn of time have had a special fascination for all of us, and the desire to touch those stars has led to advances in technology in the last century (or so) unlike any technological, scientific, or engineering breakthrough prior.
I also believe in the drive for people to make money. If someone thinks that there is money to be made, they will invest money into a venture. Until recently, there was not a lot of money to be made in space exploration and space travel. However, with advances in "rocket science" and the reduced cost of doing business in getting things to space (although, yes, it is still quite expensive), building a spacecraft and launching a rocket has become something that even small companies are able to do.
And some have said that asteroid mining is the first trillion-dollar industry. What more impetous does one need to make it work than that? If you are the first company to land on an asteroid and bring back gold or nickel or diamonds, you will not only be a huge success from an engineering and technological standpoint, but also from a financial standpoint. And isn't that the aim of any busines - to be the first to market and make a bunch of money?
Now, your question is whether it will become a reality. In short, yes. Will it be a reality in the next couple of years, though? That is a different question. As I stated, the technology exists. There are rockets that can launch a spacecraft (which exist, obviously) to asteroids. NASA and ESA have both done this successfully. Landing on an asteroid is no big deal, as this has been done. (Okay, it is a big deal to land remotely on something the size of a football field while both your spacecraft and the object are hurtling around the sun at tens of thousands of miles and hour, but it is not beyond the technological and engineer capability that the companies seeking to do it have.)
Exploration of Mars and the moon by rovers and landers has proven that we can pick stuff up from celestial bodies. The safe return of the Apollo astronauts in the 1960s and 1970s proves we can get home to Earth from those same celestial bodies, and, although the Apollo missions had people onboard to get home, advances in computing technology for space mean that navigating through the solar system to get a bucket of minerals from an asteroid to Earth remotely is not the challenge it was 50 years ago.
Returning from Earth orbit at 25,000+ miles-per-hour will prove challenging, but it is by no means undoable. NASA has demonstrated with the Orion capsule in the last couple of years that heat shield technology will protect a cargo travelling that fast (the approximate speed that an object returning to Earth from an asteroid will be travelling when it hits the atmosphere).
All of the pieces are there, both from an engineering and technological standpoint and from a financial standpoint (the financial drive and backing of investors). Putting those pieces together successfully may be a different story. The companies that are trying to pull this off may have the financial backing and support of entire nations (Luxembourg, to name one), but finding the engineering talent to find the unique solutions that are required to pull these missions off is a different challenge. In my opinion, a lot of these companies are trying very hard to be successful, but the "corporate atmosphere" is not conducive to what a lot of young and innovative engineers are looking for in today's age.
Because it is the highest form of "rocket science" so far, getting to an asteroid, mining it, and returning the resources to Earth will be the biggest engineering challenge that mankind has ever met. It will be done by 2025, if not sooner (if enough money gets thrown at the problem to hire and keep the engineers needed to do it), if not a little sooner. Regardless of when it gets accomplished, it will make someone(s) very wealththy, and completely change the dynamic of mining for humankind, as well as the future of human exploration of the stars.
For more information, please request a call - I have lowered my rates - and I would love the opportunity to discuss this, and anything else, with you.
I think that mining in space is going to be driven by the ingenuity of those companies that develop the mining equipment - not by the size of the launch vehicle. A big rocket can launch a big piece of mining equipment, yes. But companies like Planetary Resources are not looking to partner with Caterpillar to launch mining expeditions to the asteroid belt. To develop the proof-of-concept that will be necessary to get the backers to fund future missions, it will be imperative that the companies that build the tools to mine asteroids and comets build small-scale technologies that can be scaled in the future. This means that the Falcon Heavy is not likely to be launching payloads to mine asteroids anytime soon, unless Musk is building those payloads.