With star forward Paul Chapman rated a 90 per cent chance by Thompson to return from a hamstring injury for next week's decider, the 20-year-old had been considered the player most likely to make way.
But Varcoe made the strongest of cases to hold his spot with an impressive 18-possession game in the preliminary final, including a third-quarter goal.
"Travis won't go out," Thompson said after the 12.11 (83) to 7.12 (54) victory.
"Travis wouldn't be considered (for omission).
"I'll say that publicly; if he doesn't get a virus he'll play next week.
"That was the best game he's played. I don't mean to be a smarty, but I was very happy with his game."
Thompson pointed to a likely selection quandary for the Cats by also praising the contributions of David Wojcinski and James Kelly, both of whom came into the team for the match.
"[David] Wojcinski did enough, kicked a goal and won enough of the ball to say he'd probably stay in. And [it was] good to have [James] Kelly back. [I'm] glad that he's got the run and Wojcinski's got the run they needed before the grand final."
Thompson said the build up would be "very similar" to last year's Grand Final.
"There was proabably more euphoria last year but we're just as motivated, we're just as driven," he said.
"We're thankful for the experience of last year but it doesn't do that much for you in the end. [We're] just looking forward to the week.
"It's the reason why we play, why we exist really. There are 16 teams that start off at the start of the year and it gets down to two and we're one of the lucky two and we're very happy about that."
Varcoe insisted he hadn't been told by Thompson that he would be selected for the premiership-decider.
"He hasn't said that – in those sorts of words," the youngster said after the match.
"I'm happy just with tonight and I'll soak it all up. I've just got to recover and then I'll worry about those things during the week."
Varcoe said pressure for spots within the team was a healthy thing, and playing for his position was not his priority. He added that missing out on last year's Grand Final had not greatly concerned him, as the team objective was paramount.
Varcoe was unable to win a place in the 2007 premiership team despite playing 18 games in his debut season, and has had to overcome hurdles, such as foot and shoulder problems in his short career.
"It has been pretty hard, but I always try and think that there are probably people worse off than me," he said.
"Poor old Matty Egan, I feel for him very much.
"'Prisa' [Brent Prismall] was up in the stands with me last year as well and we watched it and he was going really good, but all of the boys are feeling pretty sorry for him as well."
