I personally see us bringing in a couple UFA veterans to anchor the bottom six or the 4th line to bring in more experiences to help this team win. As good as MacEwen looks, he is still a longshot from making the NHL. Mackenzie is also a long shot. And usually teams don't just have all 12 forwards out of players they drafted, and it's more likely to bring in some UFAs to play up and down the line up to bring some veteran guidance to a young line up (we may even see a UFA top 6 forward by the time we are contenders). I see Granlund remaining with the team because of his versatility. Lockwood would get a shot on either the 3rd or 4th line to start his career like Jannik Hansen.
On defense, I think Del Zotto has a good chance of staying with the group when the rebuild is over. Tanev and Gudbranson would probably both going to be here. Tanev is by far our best defenseman currently, and by the time we are contenders, he should still be a good enough top 4 D man. It would be interesting to see if we end up with Dahlin (just dream big ) and see what we do with our LHD. Currently, Juolevi, Hutton, Pouliot and Briseboi are all LHD, if we end up with Dahlin (who is also a LHD), then Del Zotto might be the one to go and we will have to make a decision to keep one of Hutton and Pouliot as they both play a similar style game.