Yeah this is the issue WotC have created for themselves.
They've gone out of their way to say this isn't a new edition, and isn't necessary, and you can keep using your old books just fine BUT also here's $100-$150 of "updated" books you "probably should" buy.
My feeling, based on 3.5E is, with that sort of messaging, a lot of people just won't or will only gradually pick up the new books. The advantage this has it's after 9 years of release, not 3-4, but an awful lot of people only got on-board with D&D in 2017 or later, so for them it's a much shorter period.
I suspect to Dan Rawson and the upper echelons of WotC, that's not a major concern, because they see the future of D&D in distinctly digital terms and I don't think the long-term intention is that book sales are the primary part of that. They may well have a deal to upgrade on Beyond or where if you subscribe to the 3D VTT, you get the 2024 content for free as long as you stay subscribed or something.