Dallas will have one of the more interesting off-seasons in the league as their window is still wide open and more young talent looks primed to join them next season. Their priority should be addressing the defense; they most played 5 d-men throughout the playoffs, with one of them being Suter and another being an injured Tanev. Tanev looks like a great fit in Dallas and if I were Nill I'd try and return him, while buying out Suter who is clearly rinsed and isn't top-6 calibre on a Cup contender.
Going into this season I thought their defense was their most significant weakness and could end up preventing them from winning the Cup. Not sure if that turned out exactly as I had predicted, but I don't think I was too far off as key players like Heiskanen looked gassed towards the end of last night's game from playing too much.
Lots has been said about Johnston (positive) and Pavelski (negative), but I thought Benn had a really outstanding playoff run leading the charge physically, doing what he could to set the tone, and using his size and strength to win puck battles all over the ice and create opportunities for his linemates. I liked him with Johnston and Stankoven. Seguin was good too, I thought. Hintz didn't look 100% and Robertson wasn't as productive as a result. Duchene and Marchment were a good 3rd line (if cap space permits, Nill should return Duchene). DeBoer seemed hesitant to demote Pavelski early in the series, and I think that cost Dallas. He simply wasn't good. As a neutral observer I had to laugh when I saw him out on the PP in lieu of Johnston.
Overall, Dallas can more or less run it back with the core group, address some gaps on defense, and be a Cup contender again next year I think. Solid organization and a pretty fun team to watch.