Here's the definitions of especially by Oxford Dictionaries:
1 used to single out one person or thing over all others:
he despised them all, especially Sylvester
a new song, written especially for Jonathan
2 to a great extent; very much:
he didn’t especially like dancing
[as submodifier]:
sleep is especially important in growing children
The example in the question uses the first definition correctly. Usually especially is applied to a single thing, and although several countries are mentioned, it's referring to those countries collectively.
Especially was incorrectly used for comedy effect in The Simpsons:
Sideshow Bob: Madam, your children are no more than a pair of ill-bred troublemakers.
Homer: Lisa too?
Sideshow Bob: Especially Lisa... But especially Bart.
"Do you think they shouldn't attend that school? What if they would become great musicians?"
This example sounds awkward and mildly ambiguous to me. The ambiguity arises from the fact that would can have the meaning "strongly desire [to]," as in the movie title The Man Who Would Be King. So one reading of the second sentence above is:
What if they strongly desire to become great musicians?
But I suspect that the speaker has a different meaning in mind. Unfortunately that meaning is somewhat obscured by the omission from the second sentence of the intended condition under which "they" would become great musicians in the what-if scenario—namely, that they attend the school. Adding that condition to the second sentence is easy:
What if by doing so they would become great musicians?
or:
What if they would become great musicians as a result [of attending it]?
By introducing the condition into the what-if sentence, we avoid any possibility that readers might read the would in that sentence as meaning "strongly desire [to]." The use of "would become" in place of "became" is somewhat colloquial, but in an informal setting it seems reasonable enough.
"Do you think they shouldn't attend that school? What if they became great musicians?"
Because would has vanished from the scene, the second sentence in this version of the example doesn't have a built-in ambiguity. But the example still works better (I think) if we add the implied condition to it:
What if by doing so they became great musicians?
or:
What if they became great musicians as a result [of attending it]?
Is there any sentence where what if + would is grammatically correct?
It's not hard to imagine snippets of dialogue in which using "what if" + "would" is the most coherent and natural-sounding way to handle a hypothetical scenario. For example:
Person A: I bet you'd eat a whole coconut cream pie right now if you could.
Person B: What if I would?
Best Answer
It is grammatically fine, but it does sound awkward. To me it’s not the sequence because since so much as the multiple conditionals. It reminds me of sentences like I went, but I left my hat behind, but that’s OK. I would rephrase it.