The Leafs entered Sunday more than $2.1M over the NHL's $82.5M salary cap, but if all works out according to plan, they'll be salary cap compliant by Monday's 5pm deadline with $4 USD to spare before placing Timothy Liljegren on LTIR.
The bad news here is that after signing Zach Aston-Reese to a 1-year, $840,630 contract, the Leafs will have to shed $796,663 to become compliant, which is within those $4 aforementioned dollars of Nick Robertson's $796,667 cap hit. Long story short, Robertson is going to be sent down.
The silver lining here is that, if this occurs, Robertson is likely to be called up on an emergency basis and should start the season with the Leafs. As far as where he'll be when the Leafs are back at full health, it's tough to say. Since he does not need to clear waivers to be sent down, Robertson could be the team's primary up-and-down option between the Leafs and the Marlies to avoid losing guys on waivers.
The Leafs will still need to clear out a contract if they want to activate Liljegren when he's ready to come off of LTIR next month, but at the very least, this buys them some time.