Won't all of those existing TP-Link routers continue to work and be unlocked to flash whatever you like on them ?
Further, aren't there sufficient TP-Link parts in the supply chain from the last 4-5 years that you'll continue to be able to source them ?
Genuinely curious...
But eventually the supply will dry up and all that'll be available will be these locked-down routers, unless you're happy to use 10-20 year old hardware, which (if it even still works) will leave you out of whatever modern, advanced features routers have in 5-15 years. If some other frequency band becomes popular with mobile devices, or some new 802.11* standard comes about that's a big improvement somehow, then you won't be able to use that. Open-source projects like dd-wrt and OpenWrt will die out; who wants to keep working on a project that only works on ancient hardware?