Well, I guess if Turbine ever gets around to adding a 8th server, they could try to make it VIP-only to see how it goes. If it doesn't work out, just switch it back to the same as the rest. This is the "1st server: Same game, no perks, just requires a subscription to play on it." as Martell proposed. I don't ever think the 2nd type of server with benefits will ever work out - if you want bonus xp and loot, just buy the jewels from the store.
But even such a VIP-only server carries a certain risk to the F2P model - on the F2P servers, the presence of VIPs works to introduce free players to the VIP status, ie VIPs can help to convert free players to premium/VIPs. It is basically viral marketing at work.
Same thing goes for the loot jewels. Having a server where everybody gets +loot bonus isn't going to help promote the use of loot jewels. If you party with a member who uses a loot jewel and he gets better loot, you would be tempted to buy the jewels. But if everyone gets the bonus anyway, the jewels don't get sold.