I'll prob have them till GW11 and remove Lukaku after that. Obviously this is based on the games till now, and Ronaldo has crazy stats so far. If that doesn't continue I can think of having only Lukaku but I'm not in favour of removing Ronaldo, especially as his price is gonna skyrocket.
So far there hasn't been any reason to have three of them, so whoever did that was gonna lose, but you can be smart about it during those GWs as there are plenty of sub-7 mids and fwds that are gonna be good value. Those are the ones I didn't mention in my previous list.