I would be absolutely 100% shocked if Beleskey ever matches his play this season. He benefited from being on a great team with 3 forwards spread over 2 lines that require planning around. That leaves room for the other 9 forwards (And specifically the 3 remaining on the top 6) to get more ice and more quality opportunities.
Beleskey has not ever showed even an inkling of a reason to expect him to put up 25-30 goals, 50 points, until this season which so happens to be in a contract season 1 year removed from David Clarkson, who shares several qualities with Mr. Beleskey, cashed in big time on a contract. If you don't think that played a part in why Beleskey played so well this season, then I don't think you're thinking clearly. If that wasn't at least a part of why he played so well, then A: He's doing something wrong, and B: His agent is doing something wrong. Players notoriously over-achieve in contract years. Clarkson, Semin, Bickell just to name a few.
Beleskey is not a 4-5m player, he's just not. That type of money is reserved for players who create offense on their own and a player you build a line around, not a player who gets the majority of his scoring opportunities because pressure is averted to a different player on the ice.