The reality of today's NHL is that pretty much any deal you're making with significant salary (ie Forsberg @ $6M)...there's going to have to be a salary component going the other way. That's the only way pieces move in this flat cap gridlock world.
That's all Drouin is, or has to be in that sort of deal. He's a slightly better (and younger) version of what Tatar was supposed to be in the Pacioretty deal. A piece who carries a salary/cap hit that offsets Forsberg's, and can backfill on the Preds roster as a 20G-50pt sort of Top-6 piece.
Nashville can then either decide to keep him if it works out...or let him pump up his value in the minutes Forsberg leaves vacant, and find a deal to move him somewhere else and keep shuffling things around. There are always sucker GMs in the league hung up on draft pedigree, and really...i think you're underselling Drouin in the first place. He's a plenty useful Top-6 winger in the right situation, on a mediocre deal. He's just not the superstar people thought he'd become at the draft. But he's more than good enough to be a contributing filler piece with some potential follow-on value in a deal like this.
It's really either that, or taking on some sort of 31/32 year old $3.4M x 3 years bottom-6 spare part like Byron. At least Drouin is a contributing Top-6 Forward with
some sort of potential value around the league.
I mean, in that sense...it's a personal/organizational preference thing again. Just as how you view Caufield determines whether or not there's a deal to be made there on the prospect centerpiece side...i guess how you view Drouin might influence whether you think there's a workable deal in it or not. But unless you really
really personally hate Drouin and don't want him anywhere near your team for some reason...i don't think you're going to find many
better "salary offset" type pieces on offer than a 25 year old Top-6 Winger on a ~$1M/10pts sort of UFA market-ish deal.
Like...pretty much anyone who would
actually be in on a high cost "win now" deal for someone like Forsberg, is going to be relatively capped out. So anywhere you deal him, is going to expect Nashville to take back some sort of junk to make the salary work. At least someone like Drouin is potentially useful junk.