The reason Elite 4 will do so well is that many of us have been desperate for a game to improve on what Elite started for nearly 30 years. Elite 2 and 3 were technically clever but flawed, newtonian physics made the combat poor (in my and many people's opinion). The clincher for me to back the project was DB's admission that those physics meant the gameplay was not as good as the original.
Despite the many tens or even hundreds of clones, nothing has ever matched Elite - though Privateer came close and exceeded it in many ways (the world was just too small though). They have all had flaws, or just features, that stopped them giving the feel that Elite did.
I only found out about Star Citizen yesterday on the Elite 4 boards and I've backed that too. Rather than competing with each other I think having two games of this type with such a pedigree will stir up more funding and more interest.