I assumed a little over 4% each year after this one. We are still within spitting distance of the cap. Fortunately there isn't likely much bonus to worry about in '20. There might be more in '21.
I used caps of 80, 83.5 and 87 mil for those years. It might go up more than that but it also might go up less. In part it depends on how much the PA uses of their 5%. If they use it all, as they usually have done the cap might go up a little more. But I don't think that it would be prudent to plan on it going up more than 12 mil in 3 years.
In that third year ('21), Morrissey's bridge has expired. The next year Connor's expires and the year after that it is Roslovic's. Those new contracts could continue to eat up all the cap rise, plus there are lesser players whose contracts will come up for renewal.
Kulikov's expiring after the '20 season is accounted for but then Niku's bridge kicks in. The good news is that both MP (if he is still here) and Buff expire after that '21 season.
I think it gets a little easier at that point for a little while but not too long. That cap space will have to be used to replace aging players. Then it is only a couple of years until some of these long term contracts to younger players start to expire, one by one.
The only major kicker here is it's going to be tough to bridge everyone but Laine from this point on.