Not so much different versions of D&D no, but probably by doing different RPGs – e.g. a modern, paranormal, and/or sci-fi game. That would almost certainly bring more sales in absolute terms, but likely not enough to justify the expense.I don't think there's much reason to think that WotC would increase its sales - perhaps not even in absolute terms, let alone after outlay - by publishing multiple, different versions of D&D.
I'd be very proud of 5.0 as a whole, but there would definitely be aspects of it I wouldn't be happy with. CR for monsters is off, and many monsters have super-boring design (bag of hit points). There are classes and subclasses that aren't pulling their weight, like monks in general and elemental monks in particular. The sorcerer doesn't really have any strong mechanical identity that justifies their existence alongside neo-Vancian wizards – this one is definitely linked to deadlines, as the playtest had a very different sorcerer class for quite some time and when it got booed they didn't have time to design something clever. The downtime rules are anemic and near non-existent. There's very little support for PCs crafting their own items.If I was a 5e designer I'd be pretty pleased with my work. Like anything done in the context of commercial employment, it's not a pure expression of any designer's vision. But it's a cleverly-designed game: the integration of significant elements of 4e D&D while producing a game that users can experience both as a descendant of 3E D&D and a descendent of AD&D.
Some of these aspects have been fixed in 5.5, so clearly the designers identified them as problem areas. I don't have it myself, but I understand that many under-CRed monsters got a boost to where they were supposed to be, and many monsters have gotten some more interesting abilities. Not to 4e/Draw Steel/Flee, Mortals! levels, but still a little something something. Monks got a shot in the arm, and sorcerers got more juice in their subclasses to reflect their origins, at the same time as wizards got some other things reflecting their focus on book-learnin'. You got bastions for downtime.