According to Sky News:

Donald Trump has signed an executive order to open a migrant detention centre at Guantanamo Bay.

So now Guantanamo prison has been largely emptied of illegally rendered terror suspects, a new use has been found for the site: Housing up to 30,000 migrants who cannot be deported to their home countries.

Wizard idea!

However...

The optics of using Guantanamo to house deported migrants is stark - reflective of the hardline policy being pursued by Trump.

As opposed say to housing them on a disease-ridden hulk moored off Weymouth or exporting them to Albania.

Trump is all about getting value from US assets.

They can even reuse all those orange jumpsuits and shackles. Bonus!