San Andreas in the GTA5 era should be exactly the same in regards to layout and terrain as in the original self titled game.
A few modifications though.
Obviously much better graphics.
Pizza Stack are now out of business at this point and therefore all of those outlets in San Andreas should be derelict. The derelict outlets should have writing on them (and all over Los Santos) in purple and green (paying tribute to the now defunct Grove Street and Ballas gangs). And perhaps something like 'RIP Lance Wilson' or 'RIP Melvin Harris' obviously paying tribute aswell. But you should be able to go into these abandoned outlets because you might find things like weapons amongst other things(as i've mentioned before). Also when you go inside, the interiors of these outlets should be overflowing with plants and trees all along the floor. Ivy covering the walls aswell.
Ganton is the same as it was back in '92 or in GTA San Andreas. Only the Grove street gang as mentioned above is defunct. Grove Street itself is the same but don't expect to see CJ, Sweet or Kendl! The gym s still there but under a different name. The barber shop remains also but Old Reece is long gone. There are some new cloth stores that are a lot more prosperous and far bigger than in GTA San Andreas. There are some fancy restaurants aswell. So Ganton has been developed a bit and is not as deprived as it was. The Johnson household is the same but there's nothing there. Same with Ryder's house, Sweets house and Smokes house in Idlewood.
Every single large town and City in San Andreas is the same. Just slight developments have been made.
There are some different Radio stations. Radio X and Radio Los Santos are still around but ST-FR, Master Sounds etc are gone.
Las Venturas remains, again more prosperous.
There are Sprunk Factoies in Bone County and Flint County.
There are three new cul-de-sacs in Los Santos
Tenpenny drive, looking on from where Officer Frank Tenpenny died while on duty in 1992.
Madd Doggs mansion is derelict like the Pizza Stack outlets. The outside pool is now murky and full of sealife (fish, turtles, jellyfish, plankton seaweed etc). There are broken windows. You can go into the mansion. The house is overgrown with trees and plants and weeds. Also more wildlife like birds (ostriches!, seagulls, pigeons etc.) and mice, rats, (bears maybe?) etc. The indoor pool is like the outside pool full of seaweed and sealife. Madd Dogg's bar is still there. His studio is full of broken mics and recording equipment. There is a picture of CJ and Madd Dogg on a beach. Which may indicate they're living in some tropical paradise at this point.
Instead of naiming that cul-de-sac after Tenpenny it could be named after Hernandez who at least tried to do good. Or named after Officer Pendlebury?
OG Loc could still be around. but has a much different persona as in the last game. He's finally gangsta. He's now the real deal and is fearless (A good idea for a new protagonist?)
The Military Base in Ocean Docks is no more. It's fenced off and is now inhabited by wildlife. Three deranged and ferocious Polar bears inhabit it after escaping the closed down Flint County Zoo (I came up with that). Other wildlife is present aswell.
Overall San Andreas as a state is no different except some key buildings are derelict and some new areas are there.