I mean, who knows with Doughty. If he's agitating to get out of LA after this year, the return would be disappointing for them, but who knows that, and who can count on that.
The bigger, more concrete problem with the plan above is that it's completely impossible under the cap. On Cap friendly, I made the suggested trade, signed Tavares to an extremely conservative 9M (he'll get more, but stay with me), extended Johnsson for a reasonable 1.5M, and filled the rest of the team with Marlies. The hit for that team was pennies under the cap, with no allowances for bonuses (and you'd want Matthews, Marner, Kapanen, Dermott to hit those, no?), and zero plan on how to resign Doughty and Gardiner (for $2M raises, in all likelihood) and Matthews and Marner (for way, way more than that.)
Now, it would help to be able to punt Martin or Zaitsev into the sun with no consequences, and Marleau won't be around forever, but you literally can't treat team building like a shopping trip.