Dsa-dub
Yes, DSA is close to East Midlands, but so is Birmingham and did that stop FR from setting up a base there.
You also have to look at how many overnight parking stands are available in the East Midlands area against how many routes FR want to operate. Also two (or three) bases close to each other helping in playing off each airport against each other when charges are negotiated.
Will DSA happen? No idea.