Does the “a” of “I'ma” extend to other pronouns?
Solution 1:
The two lines including the problematic 'a are:
We distribute weight then matriculate into real estate
Then we assimilate, powder dealing they probably still 'a hate
Note that the verbs distribute, matriculate, and assimilate are all in the present simple tense. So it's quite natural to think that so is the verb hate.
So the question becomes, why did the songwriter put the 'a before hate? My guess is that it's probably an effort to make these three phrases rhyme and have the same number of syllables (five syllables):
Then we assimilate: Then/we a/ssi/mi/late
powder dealing they: pow/der/dea/ing/they
probably still 'a hate: prol/ly/stil/la/hate
Note that probably is pronounced as prolly, which makes the third phrase one syllable short without the 'a.
Then, why put 'a? Because that's a schwa and rhymes with the schwa in assimilate.
As for I'ma/I'mma, I think the /g/ sound is first dropped from I'm gonna and then the /n/ sound is dropped. But in they're gonna, the /g/ sound cannot be dropped in the first place, so 'a cannot possibly have been from gonna after they.