Reply #57: In fact, "gonna" is now grammatically distinct from "going to", it's become a future tense marker

[Odin2005]

One can say "I'm gonna walk to the store" but you can't say "I'm gonna the store".

Based on the fact that many people (myself included) often mistakenly write "would of, should of, could of" instead of "would've..." one can argue that "-ve" has be mentally reanalyzed into suffixes marking perfective aspect on verb auxiliaries.

Languages change, in a few hundred years it is likely that all the English helper verbs will have become prefixes, I'm gonna be stopping" will become something like "Aamenabiisyaabn" :)