Those 3rd parties should be required to provide working drivers for the hardware in their phone, in source form, and whoever maintains the OS (Google I suppose, or maybe some industry co-operation) should take it from there.
Are you advocating that Google make their OS inherently compatible with all manufacturers that give them the source to their drivers or that the manufacturer should make the source to their drivers public? Neither of those are ever going to happen.
The situation is a quagmire of Google not having control of the hardware while most manufacturers don't care to update the software. Apple of course gets around this by controlling both, but that's not exactly desirable either from my standpoint. The same problem exists with Windows where a new version (XP->Vista/7, 7->8/10) causes drivers to break and manufacturers are required to update their software for the new OS.
The solution is actually pretty simple. Either A) make your purchasing decision based on the *current* feature set and treat any updates as gravy or B) make sure to purchase from a manufacturer with a good track record of releasing updates.
(And if you're curious, most LTE implementations use OFDMA. Mathematically it's a lot like CDMA, except using orthogonal frequencies instead of orthogonal codes. The orthogonality is what allows you to pick out a specific phone's signal even though all phones are transmitting simultaneously.
That's really not at all true. Here. OFDMA just increases the usable frequency range for FDMA, which splits users into different bands (channels). In CDMA all users take a lot of bandwidth and the receiver filters them out using codes or somesuch.
"No, no, I don't mind being called the smartest man in the world. I just wish it wasn't this one." -- Adrian Veidt/Ozymandias, WATCHMEN