E: D will always be peer to peer for instancing, I have little doubt of that. It amuses me all the calls for servers, as if that will fix anything (it won't). All it would do is massively increase costs (for zero benefit).
Whatever the guys from planetside 2 are doing, it works. It's running good and there are massive battles with 80 vs 80 or such. Also mount and blade had servers wher it was no problem to go 100 vs 100. It was working well. Can't say that for ED.