The Twins need above average players across the diamond as well as on the mound. They haven't had a lot of that the last four years, which is why they've been so bad.
Escobar, believe it or not, was an above average SS both offensively and defensively. Santana was above average offensively, but he never played SS. Both are certainly candidates for regression, but this is the second season where Eduardo has hit quite well for an extended period of time. I think Escobar's issue has more to do with longevity than talent as he wore down in 2013 and again last year (though to a lesser extent). Would I trade him? For the right price.
Personally, I'd probably put Santana in AAA to see if the bat is for real and let Escobar run out there every day in the short term. But if the team is sold on Santana, then switching Escobar to a utility role is both unfair to him and minimizes his value to the Twins. As a starting SS, he has value... and quite a bit. As for a trade, if you packaged him with say Nolasco, just understand that he's being used to get out from under a bad contract, so the return is going to be underwhelming. As for a trade, I'd trade him for just about anyone that Sickles rates at a B or higher. Those aren't bad prospects (Kepler, for instance was a borderline B- prospect whose final grade was a C+), and I think a lot of people would be happy to get a Kepler like prospect for him.