Nope.. it won't blow at all... World of Warcaft... need I say more?..
so without further ado, *bitchSLAAAAAAAAAAP*
... of course i didnt mean that it's gonna explode.. don't compare WoW and SA.. SA wasn't even supposed to be an online game, and imagine that 32 players in mta race servers already make most people lag, their pings grow a little coz of their connection.. DM sends even more packets, most people's connections just wont handle that, there will be a great packet loss and that will be really :~. (Dont compare MTA:SA DM to sa-mp also, mta has a way more features that take bandwith)
MTA streams everything out when the player gets a certain distance away though, so regardless of the number of people in the server players will only get data on elements that are near them.