Except for how out of balance the Denver pass:run ratio has been with Booker, your points are valid.
it does however seem like if their stated goal is to get back closer to 50:50, those touches will go somewhere.
and since you're taking Kubiak at his word, and Kubiak said both that Bibbs has "earned a larger role", and that they want to run a lot more, wouldn't it be safe to assume those extra touches will go to Bibbs?
Bibbs could get 8-10 carries, 3-5 receptions without impacting Booker'a workload much at all. And if Booker continues to be ineffective, I could see a shift happening.
But hey, I could be completely off base here. Bibbs might languish on the bench while the Broncos remain content watching their ploddding rookie force way too much pressure on Semien to sustain drives, losing them games.
That is certainly possible. I just assume Kubiak is a better coach than that.
Today's game should be interesting - I wouldn't start Bibbs as anything more than a flex, but he should have some PPR value there on receptions.