does europa universalis 4 will be 75% off again in summer sale?

Most likely.

Art of War went to -75%, and the collection is -75 as well.

Only Paradox & Valve knows. It's not unlikely, considering Paradox likes to participate in big sales, but no-one here can say for sure.

still 23 Euros for the complete version are too much, even if the discount is 75%.

didn't get the deal yesterday, won't get it in the summer sales too unless it goes 80% OFF

Ionno.

europa universallis IV is on sale at nuuvem. It's quite cheap there

there is so many awesome dlc which costs like a normal game :<

Don't know about EU4, but i just got Might and Magic Franchise Pack. In my region it costs insane 8.45$, i can't resist and wait, hoping that this discount will be up again during summer sale, really don't wanted to miss this one. So, this is my answer - if current price for EU4 for you is very tempting, buy it now. If the price is not impressed you, wait for summer sale, EU4 will probably with discount again