I just think that a topographical map would enable better planning if one could know the terrain in advance before getting there as high ground is always important but it is also important to know how to get there and if your position is being overlooked by somewhere else I just think that most maps can do it and it would be useful so why not.
Al Basrah was originally a map created by modders(ChanceBrah & Assi) who eventually were hired on as Devs/QA. A lot of the buildings were custom made by them, and the layout was inspired by both the PR map and the actual location in reality.
A lot of Squad maps are being updated to bring them up to standard, as we have seen over the past year. It's possible some of the older out-dated maps might get a touch up to bring them up to current standard. Logar Valley is a prime example, that map was supposed to never receive another update years ago, as it was the first map made for Squad and essentially was a test project - many years later it has had it's layout updated multiple times, and recently got a terrain and foliage overhaul - So Al Basrah could be a possibility.
Only issue is working on Al Basrah would take a lot of time due to the amount of buildings involved.
Topo maps have been discussed a lot, and has been a topic amongst the devs for a long time. Here's the most recent quotes from Developers regarding Topo maps.