HI. I wonder if the History version of Anno 1404 will be available on GoG too?

Don't count on it.
Ubisoft has gone full platform with uplay now and 1404 now also has multiplayer that requires uplay to function.

Ubisoft has really gone down the shitter. Such a garbage company now. The whole History edition should of been just an update that fixed the widescreen then leave it alone. They will start to die like EA and crawl back to Steam and GoG.