I guess I'm misunderstanding what you're talking about/mean. If you've got 4 sets, then you're going to get 4 sets switched. Nothing becomes obsolete - you're gonna keep the stats regardless of the name change.

I have 4 different sets, after "exchange" I will have 4 identical sets, so 3 sets will serve no purpose, but I already paid silver to aquire - this silver now wasted, 19B.

You can sell the other 3 sets.....

I need to extract first, its huge price in loyalties or manufacturing Extract Tool.

If they intended to exchange every crystal at a 1-to-1 ratio and put the crytals in your crystal bag by default then why would they specify that you will recieve "crystals and silver coins"?

I know that PA usually arent very precise in their communication but the assumptions you are making seems very unlikely.

Ooooh, okay. I gotcha. Sorry. It's still before noon and I haven't had enough coffee. Buuut, just like Zhaeph said, you can sell them (cause there is definitely a demand! There's always like ZERO in stock)... as far as extraction goes, though, maybe they'll give us some free crystal extraction tools?

We're not even sure that the exchanged crystals will be put back in our crystal inventory, are we? 

Based on past cases, like the processing stones, a good guess would be that we get the items in our mail since they are not actually changing the existing items current effects but rather creating a new item to replace those we currently have.

That makes sense -  and would solve the crystal extraction dilemma.

That panic of yours is preventing you from understanding the process that is going to take place. When this happened with processing stones, as mentioned before, you received exchange token for each item you owned in your mail. You could either use the token to get the original item (i.e. life crystal) or you could sell the token for a specified price to a vendor.

Yes, you might imagine that you lose some silver compared to selling the crystal at max price, but it is not going to be that dramatic at all. Maybe few hundred million. But you completely forget that with this change, you will be actually getting about 18 billion surplus in your mail, because you will not have to use the three expensive sets anymore and they will be converted to raw silver.