Hi dannol,
The short answer is yes, but you assume that haulers are using incinerators, not the case at all, most use autoclaves, very large ones!
So switching from off site to on site doesn't really impact the environment that much, hard to prove green here.
And Stericycle is already in the US, in fact they are a major player in the hauling business, they own over 70% of the market in off site hauling and treatment.
JMHO