I dont believe consoles are ever getting 25 tile maps. For the same reason the PC is not getting it officially and have to use unofficial mods.
The game has some limint on the number of agents it can handle (as far as I know 16 000 cars and 64 000 pedestrians). That limit is related to the engine itself and not the HW. So without some serious update of the engine (not gonna happen till CS2) there is maximum number of cars and pedestrian you can have (even if you will buy better HW, this limit will not increase in this version of the game).
And once you reach this limit, game will not spawn any new cars (untill other is despawned). And that can lead to some tricky problems (like good are not delivered, people can not go to work, firefighters can not go to fire, etc) and that can be a little game breaking.
The game is balanced around this limit. 9 tiles are basically enough. You are able to reach the limit there. But you still wont feel the concequenecs too much. Once you play on 25 or 81 tile maps, you can encounter some starnge behaviours and problems. Basically 16 000 cars can support 9 tile city. But same 16 000 cars can have problem to fullfill needs of 25/81tiels cities.
When you use mods, you risk them on your own responsibility. But I dont believe developers will allow this officially. Then people would complain, the game is brokne, because they build huge city and it is not working.