Having sold trading cards for years, I know how a movie release can effect sales of items from franchises that seemed to have run their course completely before the movie came along.
That said, it's not a given that every comic book character movie is going to be a hit. If the movie is terrible and everyone avoids it after it's first weekend, the new merchandise (as well as vintage merch) is not going to sell as well and people may hope. I think a good example of this is Nicholas Cage (Do we call him Nic now? I forget. If he hasn't had a really great movie lately does it even matter?) in Ghost Rider. The books are still fun and sell moderately well but if that movie had been really good? Oh the profits we all could have made!
I really loved the BBC Sherlock series and am putting my personal money on Doctor Strange with Benedict Cumberbatch being a hit and am quietly scooping up as much vintage Doctor Strange merchandise (including comic books) as I reasonably can but investing for the shop is another story entirely. When investing in the shop, we need to have a little more to bet on than the fact that Mr. Cumberbatch is kinda yummy to look at (Nicholas Cage was too before the weird hair dye job for Ghost Rider and the even weirder behavior after the movie came out but I digress....) and was good in another very different role produced by totally different people.
it seems the Strange universe has unlimited possibilities to draw (pardon the pun) from. If this movie is done well it could mean sellers of comic books, trading cards and other related merchandise could do very well also.
But then, it could be an over hyped clunker too.
Time will tell...