Bitcore has returned to profitable gpu mining, where have ASIC gone?
Maybe they moved on to a Coin that's more profitable to mine.

when will exchanges start to work again?
and what is BTXm? we are going to lose all our BTTX or not?
When exchanges start to work again you have to ask exchange support team. Bitcore is not responsible for this, the wallet and the blockchain run without problems.
BTXm is a cash dispenser (atm). You won't lose anything and you don't have to worry.
