Kildall was many things, but a cutthroat business person was not one of them.
Even if IBM licensed CP/M, Digital Research would never have capitalized on the opportunity the way Gates did. IBM would have inevitably dominated its development. It took Gates machinations to screw over IBM that Kildall simply didn't have in him. Also, Microsoft wouldn't have just not existed. They would still have worked with Apple early on and eventually created Windows regardless, probably based on Xenix. And given Microsoft's embrace, extend, extinguish philosophy, it probably would have had some sort of quasi-legal CP/M compatibility layer which eventually killed CP/M the same way they did with Lotus and WordPerfect...
Any sort of alternate history where Gates and Balmer aren't hit by a bus in 1980 just isn't realistic.
