L.A.
Our son is a bit of a glutton. We had him drinking from a sippy at 9ish months. At 11 months, he started refusing to drink anything out of a bottle. I guess it was easier to get the volume he wanted from a sippy. It took us about a week to figure out that he was done with bottles. Couldn't even convince him to take a bottle at the night feed. He was completely done with bottles by 1 years old. we passed on all of our bottles to a cousin 1 week later and have never looked back.
I don't know if you have any of the old newborn nipples around, if so, maybe you can start using those on the bottles again, and that way your son might opt for the sippy rather than struggle to get formula/ milk out of the bottle.
Children are very adaptable. I know we were lucky with our DS and his self weaning, but I think that you can do either a slow wean, or go cold turkey, whatever works best for you and hubs, and your son will catch on soon enough.