I know he's inconsistent, but would I be going out on a limb to think he's capable of a 20/20 season with an avg of .270?
Yeah, I think that is going out of a limb. Hill hits 2/3 of those numbers if you are lucky. I'm seeing him more likely to top out at .250/15/15... The numbers could fluctuate a bit, but I'm not confident his HR+SB total will exceed 30. Or his AVG will go much higher than .250 unless he has some luck..
For the trade, a lot depends upon who else in on your team and whether or not you think you can compete/win this year. If you have the right pieces in play already, Hill and Trumbo at those prices (assuming Trumbo gains 3B eligibility) wouldn't be terrible. Kipnis has the most long term upside though.