I don't agree. In my opinion, John Tavares was a free asset so even if eventually they have to trade Marner or others to save money and increase their dept, the net result will look something like :
Leafs + Marner < Leafs + Tavares - Marner + player(s) received from Marner trade
Other scenarios are possible, obviously, but this is an exemple. Some might say that eventually, the decision to bring in Tavares will eventually leads to bad/difficult decisions to make and eventually bring the overall roster down, but I don't see it.