It'll be a grindfest, a real coaching/goaltending duel. If Trotz and Holtby can stay equal to Gallant and Fleury, I would hope/think that the team with more talent coursing through it should reign supreme. Truly believe that if Fleury hadn't relocated his magic horseshoe, this story is already over for them. Fact is, though, he's part of the team too, and knows how to win as well as anyone. He could be writing the second half of his own impressive story, and those wheels might not fall off.
It's up to Holtby not to saddle himself with too much pressure, while ultimately still keeping pace.
On the coaching end, from what I've seen of Vegas they like to frustrate and counter-punch, they get their way by having (mostly) good skaters who hustle relentlessly. That sucks, but I also think that Trotz is pretty uniquely suited to coaching into that kind of game. Outside of some systems peculiarities I don't think they coach drastically different games, so if the coaching can negate each other and it comes to individuals and execution, they've got enough talent to pull through.
I think it helps Vegas' cause that most players around the league seem to have "but I used to practice against this guy, he should suck, what's wrong here?" moments that can put them off their games. I think it helps Washington's cause that the guy they gave up was obviously great, and whose game should have their respect right away (not that you should outright disrespect/fail to acknowledge anyone in a film session for a friggin' Cup Finals).
idle thought, who benefits more from the fact that Schmidt is their 1D, based on the practice reps they used to take together? An improving Schmidt is nothing to shake a stick at, but is it more likely that a guy like Kuznetsov/Backstrom has figured out how to play Schmidt, or vice versa?