That's a lot of eggs in one basket. What I expect:
Thomas - could turn into a 2nd-line center, definitely not a 1st-line one. Might be a 3rd-line center a la Lars Eller, which is not horrible.
Kyrou - could be a 2nd-line winger. Could be a 4th-line winger. Will have to really blossom to get to 1st-line potential. Again, not horrible.
Kostin - yet another look, he's doing X in some other league, he'll be fantastic here! story. See Dmitrij Jaskin? That's about what you're looking at with Kostin.
Perunovich - he's going to get every last possible chance to show he's a top-4 guy. If we're lucky, he's Torey Krug in Boston up through last season. If we're not, he's perhaps Steve Wagner.
Behind them? It gets ugly among the skaters. I see 4th liners galore, perhaps one player getting developed enough to be a 3rd-liner. Walman is a 6/7 kind of guy. So is Mikkola. They're going to get playing time out of necessity, they'll occasionally make a play and people will go ga-ga over them, but the bottom line is they're not guys you're building a Cup-winning defense with.
WYSIWYG, people. This roster is what's going to carry us through the playoffs for however long it's together. When guys age out and/or leave, we have nothing to replace them and going out and finding someone is going to be expensive. We're not in rebuild now, but when we are it's going to be painful We won a Cup, though - and we may be clinging to those memories for a while.