Could we expect more than 55% off on Payday 2?

In the future, maybe.

look amazon promo :D

It was 10 usd on Amazon on Black Friday. Definatly great deal for us in Europe.

Not this year AFAIK. Being in daily or flash sale during this holiday event marks the lowest price point a game can get in Steam store. You should find better pricing at other key retailers like Amazon.

Not in this sale.

Not on Steam, unless some weird bug happens.

But check steamtrades, you can find it for 5 TF2 keys (around 9 euro from market), even less.

Brazil seller

Yes, because, they release also Payday 2.

E: Actually it is -90%

Of course. Amazon already had it for 81.25% off.