Lancaster left the role on Wednesday after England's World Cup failure.
Gatland's Wales beat England at Twickenham to help the hosts' demise and he has been linked with a move.
New Zealander Gatland is contracted to Wales until 2019 and Thomas believes "he'll see his time out with Wales and probably go back to New Zealand".
Gatland has said he intends to step down from the Wales role after the 2019 World Cup in Japan.
Thomas also believes Gatland will have "one eye on coaching New Zealand after a successful run with Wales and with the British and Irish Lions".
However, former Lion Thomas says he understands why the English Rugby Football Union might want to have Gatland in charge - even if Wales' record against Australia, New Zealand and South Africa has not matched their Six Nations efforts under him.
"I'm sure England would want to make a move for someone like him after seeing what he's done for Wales," said Gatland.
"Since he's been in charge, Wales have been an amazingly successful - unfortunately not against the mights of the southern hemisphere as much as he would like.
"But we are such a force now in world rugby and are feared and respected, and that's due to the players, yes, but also due to him and the structure he's given the players.
"So I'm sure they'd want him and if anybody could afford him, the RFU, I'm sure, could."
South Africa's 2007 World Cup-winning coach Jake White "is interested" in the England job.
Former Wales captain Gareth Thomas doubts head coach Warren Gatland could be tempted to succeed Stuart Lancaster as England boss.