Nikita Kucherov was injured for a good part of the season but came back just in time for the playoffs, where teams are allowed to exceed the salary limit. It's a huge advantage; teams essentially get a free player, often a good one.
It would be surprising if Landeskog wanted to wait to return until he's healthy, especially after missing almost two seasons. But if the Avs can't accommodate him because of their financial situation, he'll need to wait until the playoffs before joining his team.