http://www.rockstargames.com/newswire/article/45951/grand-theft-auto-v-is-coming-spring-2013.html 

A few new posters, and a new trailer will be out next week.

I would hazard a guess that actually they are already working on the next incarnation and while this is a bigger game its still old tech as you pointed out, so no doubt hasn't required quite the same level of development. Companies like Rockstar will aways get given a heads up on new hardware so I don't reckon it will be as long as you think for the next one.

this is awesome... the only reason I bought a console in recent times... was addicted to GTA, GTA London, GTA2 through uni then GTA3, GTA Vice city... when serving in Iraq someone had a PS2 with them with san andreas on - playing GTA while sat in a portacabin on an airfield on 5 minutes notice to move was a bit surreal... a couple of times I did have to pause my game, grab my kit and run out to an actual helicopter

anyway shortly after I returned to the UK I bought a PS2 and san andreas... then later the only reason I bought a PS3 was to play GTA4 (also ended up getting red dead redemption too)

I pretty much don't play computer games at all these days - but if rockstar release something, especially if its the next incarnation of the GTA series, then I'll happily fork out for a new console if necessary just to play that game,

Eeeeeeeeeeeeeeeeeeeeeeeee!!! 

GOTY 2013?

This was supposed to be for the next gen consoles, specifically the next Xbox but that was pushed back a year so they have been in a pickle with this one and it is the last big title probably that will hit the current gen.
May have some FPS issues and it may be best on PC as long as its not a year wait for it.

Scuba-diving, sharks and mini-submarines!

Delayed to September now, but at least we have a definite date:

http://www.rockstargames.com/newswire/article/48591/grand-theft-auto-v-is-coming-9172013.html

So then wil this be new console ready.
And if not, I have to ask the question of if this will sell or not and so late.
Likely E3 we will see pS4 and new Xbox. New Xbox will be more ready for prime time ANd could be on sale at xmas if not earlier because if rumours are accurate its been delayed due to kinnect bringing in a good amount of wonga.