I'm not worried about D&D. There is a good chance that I'll be using a different system for my next campaign. Doubt it will be CR's new system, even if it is great, because I don't think they'll have it released by this summer when I expect to wrap up my current long-running 5e campaign.
As I look into other systems, 5e's advantages become very obvious. There is just so much more support for the game. Especially if you run games in VTTs. For me, other than very rules-light systems, I'm just not interested in systems that don't have good VTT support. Not just the rule books and system mechanical support, but adventures with fully prepped maps and tokens. So few publishers can afford to provide that kind of support. WotC's VTT doesn't have to be the best VTT on market, it just needs to mechanically support 5e rules well. If you remove the friction of setting up and running the game online, that is going to both make the game more attractive and stickier.
Beyond that is just the wealth of related entertainment, from live-play podcasts, YouTube channels, movies, TV series, novels, and lots of third-party support and enhancements. Other than Pathfinder, I don't see any other TTRPG that comes close to providing such a rich field of products and support.
My greatest hope for CR's new system is that they have the funds to develop great support for their system in at least one of the big-three VTTs (Roll20, Foundry, and Fantasy Grounds). If they are smart, they'll also make it easy for third parties to create and sell content for their system. They have a strong fan community, who could create a healthy ecosystem of supporting art, adventures, VTT mods, and other content for the system. If the system is well designed and if they have great support for on-line play, I could see their system doing very well, perhaps rising to the three to five TTRPGs.