The 20-year-old is out of contract this summer and is unlikely to want to play League Two football next season, says the Independent.
And now a switch back to his homeland of Wales appears to be the next step in his career.
Thomas impressed for Wales Under-20s at the Toulon Tournament in France this month.
That was the final persuasion needed by Swans chief Paul Clement to make his move.
Having come through Coventry's academy, he is expected to cost around £500,000 in compensation.