I'll disagree with the author's numbers. Yes the Leafs have include this year PB on their cap next year. But in order to get maximum cap room for 2019/20 the Leafs should be paying the approximate 3.5m in PB in 2019/20. And in order to do that Horton' salary has to be include on the opening day roster. After game one he's put on LTIR for cap reason and the Leafs can add. So after Nylander and some lower RFA signings, the Leafs have about 12m in UFA....and these would be one year signing.
So actually the cap in 2019/20 is manageable, since Horton can be on LTIR during the summer (the PBs aren't big in 2019/20) and you can have no PB carryover on the 2019/20.
Without that 12m in UFA signing in 2018/19 and ridding themselves of the Hainsey/Gardiner 7m contracts, the Leafs have money in 2019.20. It's finding the replacements for Hainsey and Gardiner is the issue, right now it's Borgman and Liljegren that are options/