I absolutely loved survival in the first division and I think if you have it from the start in the second one it'll be a huge success. Please keep it! Me and my mates love to play it and it's be amazing to see it in the second one with that new beautiful map!
I just hope there are repeatable Side Missions and endless bounties without boring collection of Data like the first game. Give me action not some boring activity I have to do to enjoy it. Definitely loved Survival and moreso Underground and would love to see an expanded Underground and PVE Survival.
Just watched Julian Gerighty pretty much confirm a Survival like experience in D2 - exact words were he wouldn't be surpised to see it in D2, link below of the interview in the last few minutes
https://www.youtube.com/watch?v=PPWDwBrUNyY