It doesn't look like TI has sold OMAP5 to anyone but a few board producers, so it's not surprising they want to forget about it.
It's also not completely unsupported as (I think?) TI does pay a few mainline kernel developers who work on many areas that also touch OMAP5, similar to how AMD pays a few people to work on open source drivers for their GPUs. We might get some unofficial help from those people (already had some help mostly in form of advice), but there is no guarantee for that.
I think I have posted about this before, but yeah it looks like it's the norm in the SoC world anyway. Have you ever seen a driver update for a phone? I don't think I have, my old Android phone had an official Android 2.3 -> 4.0 upgrade, but that dragged all the same old kernel and the drivers (they were unchanged).
Want any bugs fixed? Buy a new device.