Unlikely. Because that wouldn't restore faith in the D&D brand overall, it would just show that the brand remains strong in the tabletop games category. And that's only if the investors actually believed that that's what it meant instead of it being a blatant move to manipulate the numbers by putting out a new edition rather than a sign of actual strength. I mean, it's the kind of thing a company could do but it's not the kind of thing you want to see in a company you're investing in - it's a sign that maybe it's time to sell actually because their numbers are inflated. (Now if the tabletop numbers start to slide then those kinds of games become a bit more justifiably - but boosting your strongest strength to cover up your weakness in an area you're trying to break into is an obvious scam that companies pull and can only fool some of the folks - and usually not for long).
A tanking D&D movie will probably lead to Wizards scrambling to try to show strength in other non-gaming entertainment areas with the brand. Like emphasizing other deals that are in the works for the brand. Remember how earlier this year they announced a D&D TV show is in development through eOne? That kind of thing serves double-duty - if the movie takes off and does really well then it's a "natural fit" to have a TV show with the D&D brand, if the movie underperforms then "film is not the optimal venue for this property" and the focus can be on the TV show in development as the actual entertainment venue that is going to make them money while they scramble to figure out how to get another film or animated series into development in case the TV show tanks next.