I agree with what some others have said. It would be pretty much impossible to make something like this in a real time plug in. The process needs human input and a look at the whole files in advance. Even with this you are unlikely to get a convincing morph between any arbitrary sounds.
Imagine you were trying to morph a 5 year old scottish girl's voice into a 70 year old American's. Even if you got them to say the same thing with the same timing, how would a real time plugin know when the sounds are in sync to allow a smooth morph? Even if it was in sync, the accents and dialects have very different vowell sounds, what happens when you morph between two formants? I bet you don't get a coherent vowell!
What happens if you morph between something consisting of wideband noise and a pure sine like bell tone. There is no common feature to morph and it just wouldn't sound like morphing.
There are so many cases where morphing wouldn't work, which suggests to me at least that any useful effect from it is going to be down to careful sound selection and some skill on the behalf of the engineer as he chooses the mappings, timing and pitch markers of such a process.
The best you could hope for is a plugin in which you load your two sounds in advance and can then set up what source features are mapped onto the target. You could use warp markers, pitch mappings and transission points but again, the order and rate of change of these mappings will work better for some sounds than others and only the engineer can determine what works best for the material or the effect he is trying to achieve.
I think the best way to get these effects is currently in synth parameter morphing. Synths are better at creating dog barks and mimicking real life sounds than software currently is at morphing between real audio sources.
I also think that if it was possible to do in real time we would already have it as the applications are broad. You could half morph a vocal to sound more like mariah carey etc. The abuse of autotune would pale into insignificance. Maybe it's not such a bad thing that we don't have it