Former New South Wales State of Origin hooker Peats and ex-Hull KR prop Peteru both joined from Leigh Centurions on loan deals in July and have had significant impacts for Giants.
Ashall-Bott signed a 12-month deal at the start of the season after Ottawa Aces delayed their start in League 1 and, such has been his form, in recent weeks he has kept regular full-back Ashton Golding out of the side.
They are all expected to face visiting Leigh in Huddersfield’s final game of the season but Watson fears he will not be able to keep them for 2022.
He said: “Those three at the moment haven’t got contracts but they have been very important for us over this last period. Out of the last nine games, where we’ve won five, they’ve helped us win; if they’re not there then we don’t win.
“The impact of Nathan Peats has been exceptional playing on the back of Nathaniel Peteru who was outstanding again in last week’s win at Catalans. Olly Ashall-Bott has come in and really claimed the number one jersey over the last month and a half. He just feels like he is getting his career started as this is his best run of games he’d had in Super League.
“Ideally we’d love to keep them but the salary cap and quota spaces will mean that might not be possible. It could be their last game and we want to send them out on a win as they have been outstanding for us.”
Watson says the club are expected to announce imminently the signing of a new hooker to join Adam O’Brien in 2022 and revealed James Cunningham has already left the club despite having a year left on his deal.
He is not the first to depart and the coach conceded he has found out the “harsh way” about who was up to scratch in his first year in charge.
Watson added: “It’d have been quite easy to stroke egos and paper over the cracks but I felt what we did this year was necessary for where the club need to be going forward and we’ll be better for it.”