This sounds great but I don't know how we would do it? changing map pk3 isn't a great idea as it would change the original maps causes issues with downloads as the name will have to change.
Also who is going to make all the maps? who is going to make map for the maps when we change them? we won't just be able to add maps when we feel like it we will have to wait for the maps to be done. We would also need to discuss every spawn killing point on every map before they are made.
So if you guys are really serious about this then you need to think about everything above and how it all will happen.