Anbody know DOTA 2 Quirt's Summer Key vanish tomorrow?

No, they will be just act as normal keys then.

I thought keys for events would just become normal default keys after a certain time.

it will become normal key (brown one), like TI3 key

It will not actually disappear, it will revert back to normal keys, unless you put it in the market then some sucker decided to buy your key, the key he bought will revert immediately back to a normal key.

Thanks for all answers. So anybody know when this happen i mean which timezone.

Special keys never disappear, they just revert to normal ones if the promotion they're tied to ends.