Hypothetically, TB might value Danny and needs a DH. They take defensive metrics very seriously, need another middle infielder, and he is still on his pre-arb salary. Put Danny and Morse in a package for Shields, and have Moore and Tracy split time at 1st.
TB would undoubtedly prefer moore over morse. Moore still has 5 years of team control left as opposed to Morse's 1.
I would imagine that Danny and Moore could be a start to a Shields deal.