It's no secret that the Leafs were shopping Andersen this summer and looking to get a goaltender with more term, and equally capable. With the season starting soon, it's likely that Andersen plays out the season and ends up going to Free Agency. He's gonna be 32 before the start of the 2021-22 season. The Leafs likely won't be extending him as he'll be past his prime and probably asking for too much. I could see the Leafs trying for no more than a 2-year deal, and MAYBE 3 years if there's a discount, but I doubt it. With that said, it seems likely to me that this will be Andersen's last season with the Leafs, so let's look at options the Leafs can target in free agency next summer (it'll probably be Fall actually).
Courtesy of spotrac.com, the highest paid goalies becoming UFA's next year are Tuukka Rask (7 mil), Pekka Rinne (5 mil), and Frederik Andersen (5 mil). The ages of these goalies are gonna be 34, 39, and 32, respectively, prior to the start of the 2021-22 season. The Leafs will not want to target these players knowing that their age could make their performance drop drastically. Let's look then at the youngest goalies becoming UFA next year that have some decent experience.
We get Jordan Binnington (will be 28), Linus Ullmark (28), Phillip Grubauer (30), Petr Mrazek (29), and David Rittich (29). Offering upto 3 years to any of these players would probably be a safe bet, and 4 years being risky with some. Now let's jump into the numbers of whether these players could even play as starters.
Mrazek is clear and away the most experienced with proven experience as a starter in multiple seasons, but those season were 3-4 years ago. Let's see how these goalies have performed in the past 2 seasons. Among goalies who played more than 30 games in each of the past 2 seasons, here's how they stack up at 5v5 (courtesy of moneypuck.com):
Each of these goalies' performances this coming season will definitely matter too, but with the data we have for the past 3 years it's evident that Binnington and Grubauer would be the best options. With 25mil in cap space next season, St Louis will definitely try their all (and should be able to) keep Binnington easily. They don't have any other capable starter either, so re-signing him will be a priority. I wouldn't bet on him reaching free agency.
Colorado's lack of goalie depth was exposed in the playoffs this past season, and with over 25 mil in cap space, they should easily be able to re-sign Grubauer too if they want to, which I'm sure they will. That leaves the last 3 decent options as Mrazek, Rittich, and Andersen. Rittich is likely to hit UFA as Calgary has Markstrom now. Carolina will have the space to keep Mrazek if they want, which they probably will considering their other goalie, Riemer, will also be UFA and 5 years older. It comes down to keeping Andersen on a short term deal and hoping he performs, signing Rittich (or Mrazek if he becomes available), or trading for a goalie. It doesn't look great for the Leafs right now, and it looks like giving up assets in a trade might be their best option. Or, maybe Andersen agrees to a short-term deal - who knows with the current situation.
Other UFAs who will all be 31 or older for 2021-22 include Jonathan Bernier, James Reimer, Anders Nilsson, Antti Raanta, and Devan Dubnyk. Dubnyk and Nilsson have both been atrocious recently, but the other 3 all had a positive "Save % above expected", with Bernier doing it over 46 games with the Red Wings.
It'd be funny if there was a Leafs reunion with Bernier.