People can buy ALA with fiat as well as I understand, but without discounts. And ALA will not be trading on exchanges?
That's right. You can buy ALA for cash in special shops partners, there won't be discounts since you buy it with cash and it won't be traded on exchanges.
How it will be calculate ALA price in fiat even if ethereum price going down. Mostly all ICO have related price to eth or btc.
ALA prices will be pegged to FIAT and only ALX will be tradable on exchanges with the key that if you will change ALX to ALA you will get the ALX price in FIAT plus 20% in ALA. But you cannot exchange ALA to FIAT. You can sell it to someone who wants to buy games and apps or buy them by yourself.
Wouldn't it be theoretically possible to also trade ALA vs fiat? For example if an exchange provides a trading pair for that? Or can ALA not leave the system?