I agree with this, and I'd like to elaborate.
1) Fans agree that adding Radulov and Markov would not make this team a contender. If that is true, adding two great players doesn't make the Habs a contender, it just makes them a playoff bubble team. Zadina and next year's top-5 pick will not be enough. Thus the Habs need 3 top-5 picks.
2) Pacioretty might be lost too, hopefully he can be replaced by something equivalent, say a trade for a good, young forward.
3) Given the above, the Habs need 3 top-5 picks. However, due to injuries and busts, if your team needs 3 top-5 picks, you probably need to draft 4, and thus the Habs need 4 top-5 picks.
4) Moreover, Price and Weber are likely to be declining soon.
It's possibly going to be a long road. The first saving grace is that the Habs do have cap space, so if there are good UFAs in 2019 or 2020, they can take a shortcut. The potential second saving grace is that the farm system is improving according to some. If they can get some impact out of Poehling, Scherbak, Juulsen, Ikonen, etc then that will go a long way.
But even if things go well, I think the Habs will need another top pick in 2019, and possibly in 2020 as well.