That seems extremely unlikely.
Inter are reportedly being forced to sell one of their prize jewels (Bastoni, Lautaro, Skriniar) this summer because they need to raise funds. Why would they give a bunch of that money back immediately in a massive loan fee, much less commit to give the rest of it back (and more) with an obligated buy for an aging striker on huge wages?
Marotta is a very savvy operator in the transfer market. My guess is that he will take Lukaku only if he can loan him for a year relatively cheaply, especially as this might smooth things out if they sell Lautaro.