Ugh... no. I'm not opposed - a good pvp mode in Diablo could be a lot of fun. The problem is money and expectations.

We're going to expect an incredibly well-made campaign that could be a standalone AAA game on its own. Knowing BLizzard, they're probably going to try to go overboard on making a good story-rich campaign, since D3 had an underwhelming story and it was the one piece of vanilla D3 they could not go back and fix. Then we're also going to expect a compelling endless pve mode similar to D3. And then we're going to expect seasons, new sets and legs, and so on. The "typical O&M" that is actually still a significant development undertaking.

And the problem is we will want D4 to still be a buy-to-play game. That's a ton of content to wish for when Blizzard gets nothing beyond the up front $40 or $60 from us. And now we want to ask for pvp as well? And having it well balanced with pve? It won't happen, unless Blizzard further monetizes D4 from the onset... and I reckon they'll be cautious about that after the RMAH.