Some help with Khmer special ability

[Suisight]

So the imo central Khmer ability is that districts on rivers (and navigable) don't remove the tile yields. Makes it insanely attractive to build them there. I'm unsure though how this plays out in the long run:
Do districts placed that way keep this ability in next ages - making placing them whereever possible basically a must-have?
Or do they lose this bonus in the next age - meaning one should be careful with placing them?

I could of course try it, but figures asking would be faster.

[Rhapsody]

Originally posted by Suisight:

Do districts placed that way keep this ability in next ages - making placing them whereever possible basically a must-have?

No. But being able to retain river tile bonuses on urban tiles is a benefit that probably won't too significant in later ages anyway.

[Suisight]

Thanks