Uber cool plan mooman. mooman has suggested this previously but not on this scale, also Pyro suggested something similar, although it was geared towards a Ghost Mode SA-MP Update. (We're been told, that won't be happening anytime soon.)
I think this is a great idea. A one world replay, that would be awesome.
As pod posted though, the data usage might be a bit too extreme, that's the only problem*. pods bot system could also be used to easily load the replays. As mooman found out, adding bots to server is very easy thanks to the bot systems config files.
*Another problem could be 40 players recording paths, we've probably tried it with about three players recording without any problems. As with any update (especially mine lol), we won't know till we try.
Rac3r when will you comment on this lol
Does help if I'm on online.