Yes if there's potential then there's a massive premium on that
If we’re going for potential then I think what people mean is Lukaku when he first joined / signed potential rather than Lookman / Vlasic potential.
If they do mean the former then, as you say, you’re looking at £35-40m in today’s prices.
Then there’s the fight on for them if a CL team also has an interest.
If it’s the latter, who are cheaper and easier to sign, we already have those types here.