In theory, yes; In practice, not likely.

HMD definitely does not want Harmattan, as by itself it is only part of the game; they would have to resurrect all the backend stuff for SW update and application marketplace from zero as nothing remains in place.

Using Android they can leverage Google to do the heavy lifting so my guess is they are going to revive only the physical form of the N9 device, creating a zombie-from-the-grave that looks like the real thing but runs standard Android as the operating system.
Very probably it is not even going to have a swipe-enabled launcher.

That, of course if any of this rumour is true.