No - the slow cook method he has employed, seems to venerate, does not turn around quick results. Even if the team becomes top flight and is a constant challenger for the cup, the 5 year time-span seems too short to realize this ultimate goal. Few teams have done it the slow cook method and reached said heights. The Nashvilles and Winnipegs (currently successful teams that were built primarily through home-grown talent, limited hockey trades for needs) all took longer than 5 years to matriculate to this point.
By Hextall's own words, he's only really 2 years in, so an additional 5 years from now makes 7 years (or 9 in real life). This summer will be Chevy's 7th (becomes null if they win). Polie has been at the job since forever.
Vegas is an anomaly. Chicago and Boston could be comparative, although I think Chicago took advantage of a new landscape coming out of the 1st lock-out and adapted to the new NHL better than most, Boston was the last vestige of the old NHL working. The Flyers do not have the coaching to reinvent the game on their terms to attack the league on a different, unaccounted for access to exploit advantages (minimize weaknesses). LA is probably the best reason to have faith, how they won and Hextall was actively present for the 1st.
TL;DR - the talent level may be on the cusp of Cup winning; have no faith in the coaching to get us over the hump, doubt talent will trump coaching enough to secure necessary wins; have not yet experienced a reason to have faith GM can make a successful win-now move; 5 year window too short (maybe 7+, yes).