I'm very much hoping that Howard plays a part in the sequel as some kind of con man, or a role like the Collector where he has a load of old space junk and the team have to barter with him or some such. I doubt he'll join the team or play a major role, but I'd love to see him explored, maybe sucked into an inter-dimensional rift so he can cameo in other MCU movies (it'd be amusing to see "Howard for President" signs/badges/headlines in various MCU productions). For all the flack Howard gets, I don't see how his inclusion can really hurt when it's just a bit of fun.