If that time is spent creating a game as amazing as GTA V, I'm perfectly happy waiting another five years for GTA 6. And I really doubt I'm going to be the only person on this website to feel that way.
Ultimately it's not THAT far removed from GTA IV, using elements of RDR mostly, not that that's bad in any way, but the detriments that still exist, as I pointed out with car collisions, and some minor handling, planes seem near to non-existent in the skies overhead, you can hear and not see elements around you, but that maybe due to sound design not taking into account visuals, I'll point out as well; the sound of planes close by or lawn mowers running, I've seen them lying dormant as yard fixtures but no actual peds mowing. It's still early though.
Crashing a car, let me give an example, in the USA any production car has to pass safety standards, have certification and can often encounter severe penalty if it's deemed unsafe, in crash testing speeds of 5 MPH do produce damage, and speeds under 50MPH can also cause severe cost damage to your wallet. I've owned 6 cars, in about 20 years or so of driving, I know this stuff first hand. In GTA gaming, you don't get anything like real-life in that regard, not that GTA should be the Sims, but we hope for something less arcady, less the direction of Saints Row... just an example I think many people also would agree with
That said, development on a pre-existing platform, engine, Middleware, all should have amounted to a shorter time span, just my way of thinking about it, but they also have to work with new hired staff, and there was rumor during the delay perhaps a tear down and rebuild of part of what makes up RAGE with Euphoria, but again, time will tell.
The massive money day GTA shows is that other game makers can approach the same school of thought and perhaps win out, but to beat GTA will be damn near impossible now!
GTA isn't about realism. Its about the humour and fun of the game, their replay value. Realism isn't always that great.
I hope they take all the time they need to keep making truly great games.