Do you expect they'll sell him now after they already sold Tielemans and will probably also sell their top scorer Teodorczyk?
I know he won't be in Anderlecht in 2-3 years but he might still be there next year and if he shows enough improvement we could consider buying him then if we'll hit with all our signings this summer so we won't have any glaring holes anymore (probably just a wishful thinking I know). Even if he's sold it's possible he'll go to a club like Monaco, Dortmund, Roma, Sevilla, Valencia,... (instead of clubs like PSG, United, Chelsea, Bayern, not to say RM where he'd be almost impossible to buy) where we could still get him from if he'd prove to be the real deal.
Merino would be an interesting option for the future. BVB will reportedly sell him with both Bilbao and Sociedad interested. We can always buy him from clubs like this but right now his price will probably only be around 10M€ (of course if we'd show interest Dortmund would instantly ask for more). Maybe buy and loan him to one of the Basque teams wouldn't be a bad move but don't see this happen.
We'll see about Samper. Granada was a mess so I wouldn't really judge his performances there but yeah, overall it was another lost season for his development and time is running out for him to really made it at top level. Still think he deserves a chance in preseason to show Valverde what he can do and then decide whether to keep him in first team or loan/sell (with included buy-back option) him.