Quoting: GMBL
Without the extension, it's still pretty fair. Saros is a pending UFA and I would say that goalies aren't worth the same as their forward or defensive counterparts, even if it's a winger or LHD. Would NSH want to give a whole 1st (-Jarnkrok's 3rd/4th value)? Maybe not, I would expect that they would ask for Minten instead of Jarnkrok. I don't think there's much difference in value between Fabbro and Liljegren.
I agree with Just_A_Guess, I don't think NSH would want to give Saros, and it would probably be Askarov+ another piece (someone like Tomasino that could be a roster player) instead. Do the Leafs want Saros? Maybe. Treliving did say they don't want to have the 2nd best goalie in the series when asked about extending Samsonov, but considering that Woll could be that guy for them if healthy and Askarov's high potential, I think they would spend the new found cap to fix their defense.
I think NSH would be willing to spend in order to get a superstar or game breaking kind of player, I just don't know if Marner is that player for them. I won't say he can't be that player, but it would just depend on the cost. The big thing for NSH, if they were to give up Saros, is that they wouldn't want to give up much more than that as part of this deal, and that is more due to how much they value Saros. I think you are right that goalies are likely evaluated as lower than forwards and defenseman, but that is because a goalie can't really win you the game, they can either 1. Keep you from losing it or 2. Help you "win more" (e.g. bigger score discrepancies). That said, goalies at Saros's caliber can "win" you games just by continuing to give the offense time to score, and for TOR's case, that isn't exactly difficult.
But, if TOR is not interested in Saros, what does it cost to get Marner? For him I'd be willing to spend a number of assests for him. The only 3 prospects in my mind that are currently untouchable for Marner would be L'Heuruex, Svechkov, and Molendyk. Either of the 1st's NSH has for 2025 and some of the top prospects NSH has like Tomasino, or defenseman like Ufko I'd be open to moving. I wouldn't feel good about giving up Ufko, but I would consider him eligible from NSH in a deal that brings in someone like Marner, and NSH can draft for more RD's in the upcoming draft with their picks.
If the ask is Askarov, then I can't imagine that NSH would be very receptive to it. They aren't going to not consider it, but I'd rather try free agency before moving Askarov. The big reason for that, and with the idea of acquiring Marner is that NSH needs centers more than anything now, and NSH has an over abundance of RW's in system right now, so moving the goalie of the future for a piece to win now, when the team isn't exactly built to win now is really risky and would require a lot re-prioritization on NSH's end to make that happen.