At this point, yeah I would. I love Tanner but he's of no use to us in this doomed season. I'm not certain if the Cubs themselves are the best choice for trade partner in terms of leverage, however. It's likely that at least one contender with a marquee closer loses them to injury--Royals with Chapman, Orioles with Kimbrel, etc. which would make them willing to overpay for Tanner.
I guess the question is whether or not we trust Tanner to stay good for that long lol