Oh, and 4e has the condition track for long term matters - you could do an excellent geas on the condition track.
Umm, you do realize that 4e has curse mechanics for long duration curses right?
Never mind that the disease condition track mechanics make this sort of thing surprisingly easy to do. It's not like this is a terribly hard thing to add into 4e.
OK, so you want long term conditions - like petrification, disease and so on. That is something I would expect to (still) be there.
I don't know those mechanics because I don't play 4e. I realize that the OP started the thread as a sort of criticism against 4e, but I all have been saying is what I want from 5e. I assumed that the OP write correctly about 4e missing something, but it doesn't matter to me.
If those mechanics are good enough then they can just port them to 5e. For curses it is important IMO that the magic remains, now technically I don't bother if it is the spell having a long duration or it is instantaneous but the effect lingers on.