Er, I should start off by saying, "I'm an actual former stockholder AND I've been to Hasbro stockholder meetings". I do think I might have a better insight about the WOTC& Hasbro relationship.
True, Imy last meeting I attended has been almost a decade ago, but I haven't heard anything change about Hasbro itself.
Hasbro is somewhat infamous in its hands-off approach to its subsidaries. I distinctly remember other fans of Hasbro's other subsidaries basically asking the same thing. Will Hasbro gut my favourite "company" after they acquire it? The answer was all the same. NO.
Hasbro doesn't look at SPECIFIC product lines but the overall revenue of its subsidaries.
Hasbro, most assuredly, probably doesn't even know exactly the profit to cost ratio of D&D and even if it did, it wouldnt care one iota as long as the overall WOTC division was successful.
Keep in mind that even with 4E's relative success, I seriously doubt the line was even as half as profitable to WOTC as M:TG (no-brainer) but also even the NOVELS department (really, I have a suspicion that even the novel department probably challenges M:TG. Really, profit to cost ratio for novels has to be much, MUCH larger than even M:TG)
Given how more and more "lines" seem to fall under WOTC (contrast the WOTC that Hasbro just bought to WOTC of today), Hasbro obviously seems to think WOTC is a very good subsidary. (Really, check out Hasbro's other subsidaries that have basically stayed the same size as before)
Personally, I think the BIGGEST issue that Hasbro might be looking at WOTC is the Dreamblade line that crashed and burned given how many resources WOTC put into it.
THAT, might actually cause Hasbro to take a look.
Similarly, the change in the M:TG release schedule I think was *influenced* by Hasbro (previously, M:TG had a release schedule where there were 3 releases per year and the next year, there would be 4 and then back to 3 and then to 4 etc. Two years ago, they went to 4)