I think there will be a work stoppage. As long as Goodell is the commissioner and Smith the NFLPA boss, the animosity between the two is real and in Smith's case personal.
And no way the owners ever give fully guaranteed contracts, injuries without salary cap relief would hamper teams ability to stay competitive. And the real high odds of injured players piling up tons of cash while never playing again is something the owners won't go for. Imo