"Yeah, most probably at this stage - he is a great loss," said Anscombe when asked whether his star blindside would be heading elsewhere.
"I don't know if it is signed or sealed at this stage that's for Stephen and his support team to make those decisions.
"We haven't had a lot of him this season because of injury, but he is a world-class player."
Ferris was in superb form on his debut Lions tour before injury ended his hopes of a Test spot prematurely.
He was one of the stars of the initial weeks of the last Lions adventure, scoring tries in each of his two appearances against the Golden Lions and the Cheetahs in Johannesburg and Bloemfontein, and he had been keen to surpass that success with Britain and Ireland's elite this time around.
But injuries have plagued his progress ever since, with knee, back, calf and ankle problems seriously limiting his involvement for club and country.
Calf damage prevented him from participating in Ireland's summer tour of New Zealand and a back complaint hampered his early involvement in this season's PRO12.
He had surgery on his ankle at the end of February after missing Ireland's entire autumn and spring campaigns and is currently expected to be sidelined for three months.
That latest setback has all but ended his hopes of a place in Warren Gatland's Lions squad after he had been seen as a firm favourite for a starting spot against the Wallabies at the Suncorp Stadium in Brisbane on June 22.