Since the game is played P2P, the server connection is hardly an issue, especially since the current server software was developed in-house (they moved away from the leased stuff BB originally ran on). The match-level client communication, however, is still the same, and is based on the system used on those originally leased servers... but hey, they didn't write that in the first place, another company did, so they'd still have all the original documentation for those libraries.Quite frankly with no one left that knows the pc version client code I'm surprised there even is a version coming to any format built on the premise of linking to the same core game server.
I'm still skeptical about P2P matches on mobile devices, myself. While its no doubt possible to do, I have a hard time imagining that many mobile internet providers are oblivious to the dangers of allowing the internet to send unsolicited data to mobile devices on their network, and as such would likely have their routing systems set up in a far more restrictive manner than home broadband.
If not for the fact that the match communication's (bad) system is so integral to how the game works, I'd assume they were replacing it with something that allowed for more reasonable server-based match communication rather than P2P. Replacing the old system with a better one, however, would absolutely require a lot of reworking of the game's internals, and as you say, there's nobody left from the original team that I know of.