I think it's a tad unrealistic to expect Johnson or Killorn to produce at the same clip with the worst team in the league as they did with the best team in the league. They would both likely see a significant dip in production going from the powerhouse Lightning to the bottom feeder Red Wings. I wouldn't expect anything more than 0.5 point per game players at best.
With the flat cap, I don't see any top teams being able, let alone willing, to give up premium assets for middle six forwards at the trade deadline. They're also not likely to acquire these players with 2-3 years term remaining. If we were to trade for Killorn and Johnson, I think both would be Red Wings for the next 2-3 years respectively (unless one were picked up by Seattle).
The Toffoli comparison kind of falls apart when you realize the contending team was acquiring, and the bottom feeder team was giving up the player. That's the opposite of this situation. If we had a Johnson and / or Killorn, and Tampa had cap space, I'm sure they'd be willing to give up similar pieces as Vancouver did. That's simply not the case though.
I'd do a straight up hockey trade for Killorn as well, if we were in a position to do so (aka a contender). Making that sort of trade now would be counterproductive.
Tampa need to shed salary cap space. Detroit do not need to add any more players. They do not need to add salary. If Tampa want to trade either of these players to Detroit, it should come at a premium. A late 1st round pick isn't that, for that much AAV and term. Don't do any team, let alone a divisional rival, and current Stanley Cup champion team, any favors.
Yzerman has made it abundantly clear through his moves this offseason and in his press conferences, that he does not want to handcuff the team with long term contracts. He wants cap flexibility. It's a very smart way to navigate a rebuild. Adding both Johnson and Killorn would go against everything he's done and said up to this point. The only way he does it, is if it's a massive boost to the rebuild. Again, a late 1st round pick just isn't it in my opinion.