Well for Microsoft. The 100 FL cap was due to Halo 2 and how its friend's list system worked(it capped out at 100). And since people STILL TODAY fucking play that shit, M$ is unwilling to expand pass that cap.
PSN, I dunno about. But they are in the talks of having a premium service you can optionally pay for. (You'll always be able to play online for free) Maybe they'll extend the FL cap that way, as a feature?