I think it would be imprudent to rely on Ensberg as a long-term solution at third base.
I'm as big an Ensberg booster as there is, and while a low batting average can sometimes obscure the value of a solid OBP and decent slugging percentage, the fact remains that after ripping the cover off the ball in April (.329/.467/.765), Ensberg batted just .209 and slugged just .377 the rest of the way. Granted, he did have a .374 OBP over that span, but that doesn't make up for the dismal average and power outage. He did enjoy a nice recovery in September (.273/.421/.477), but I'm not inclined to put a lot of stock in that small sample size.
For the season, Huff batted .267/.344/.469, which is virtually spot on what you would expect based on his career numbers (.285/.342/.477). There's a lot to be said for consistency, and Huff has turned in the same performance, give or take 10 percent, for a few years now. He's not going to threaten for MVP honors, but in a good year he's a candidate for a reserve on the all-star team.
They should be striving to sign Huff, but I also think getting rid of Ensberg when his trade value is very low, particularly given the great things he has shown himself capable of in the past, would not be a good use of resources unless the deal were just right.
In other words, I don't understand keeping Huff and keeping Ensberg to be mutually exclusive unless they cost too much combined to keep around. If Ensberg gets his stroke back, they can put Huff in the outfield and enjoy nice production from both. If Ensberg doesn't work out, they can use Huff at third base.