Would it be possible to create the entirety of London in its full size as a map mod for GTA IV?

Or are there map limitations to memory or the CPU, etc?

There might be a problem with missions and AI path, if you keep it to low poly buildings you MIGHT make it if it's as large as iv's original map

Would it be possible to create the entirety of London in its full size as a map mod for GTA IV?

Or are there map limitations to memory or the CPU, etc?

Most likely no. The reason NY works is because it was done by R* professionally and it was scaled down. London at full size would most likely not work and would definitely crash a lot. Everything would have to be redone, including mission starts, LCPDFR locations and all that. Closest you'll get is proper road markings and traffic and the like.

The entire of London to scale? No, definitely not. You could probably recreate parts of it but it'd still be a mammoth job and I doubt anyone will undertake it anytime soon if at-all.