3v3 is what it is. I think SEMC has taken it about as far as it can go without major changes, such as a new map. (Ffs, why no new map in 3+ YEARS??) I think we’re unlikely to see much attention paid to it for quite a while, as 5v5 is (and should be) their main focus for this year.
I agree with the frustrations you mention – I play soloQ a lot out of necessity, and I am constantly stuck with weak carries, selfish junglers, or incompetent captains. The only silver lining is that in 3v3, it’s possible to hard carry your team if one member (or in some cases, both other members) sucks. Good luck doing that in 5v5