Given that D&D is now a lifestyle brand, I don't think a boycott will really hurt them - as long as you remain engaged with D&D in any form, you're helping them.Gonna phrase this as politely as I can. Specifically I'm advocating burning 1D&D down to the ground and all the D&D branding. Thus includes online play, the movie, video games, new edition everything. If you play MtG you can make your own decisions.
Essentially boycott everything WotC/D&D related. If you're feeling motivated throw in Hasbro and MtG related.
So you'd need to stop playing any edition (switch to another game entirely, and obnoxiously correct anyone who refers to it as 'D&D'). And only ever speak about D&D in a negative light.
The one thing most likely to hurt them is to consistently refer to the upcoming movie as a "crappy remake" - as far as possible, tie it to the cinematic abomination of the 2000's. (It helps that the director of that one is credited as a producer here.)
The problem being, of course, that to be successful you would need to damage the brand, and that may not be desirable.
One last thing: I do think any talk of "going nuclear" is still premature. It's just about possible, although unfortunately I think unlikely, that WotC will reverse course on this. So I would be inclined to wait until Friday before doing anything drastic.