trouba wants 6+, dekeyser wants 5, mrazek wants 5,

so between all 3, cap room is impossible, i think the trade is realistic tho

Hm that might be true but looking at the comparable contracts, Trouba probably isn't getting 6+
This year:
Seth Jones signed for 5.4 over 6
Morgan Rielly signed for 5 over 6
Olli Määttä signed for 4.083 over 6
Sami Vatanen signed for 4.875 over 4

Dekeyser might get closer to 5 but I highly doubt he's going to push for too much.

Mrazek will probably get more but I really don't think he's getting 5 unless he's getting signed long term:
Jake Allen signed for 4.35 over 4
Frederik Andersen signed for 5 over 5
Andrei Vasilevskiy signed for 3.5 over 3

Overall I think I might be 1-2million off but that should still be fine. But I'm not sure about the trade anymore though since Pulkkinen is out untill fall :/