Ancient-Red-Dragon: I'm not sure why it matters if there is one or not.
How would the alleged "10th Anniversary sale" be any different than any of GOG's other big sales? IMO it wouldn't.
The same games that have been on sale in their other big sales would also be on sale again, at around the same prices as in GOG's previous big sales.
The few ones that have a newly-large discount would have it because of those game's age, not because it is an Anniversary sale and the devs have a special sentimental attachment to GOG. And those same new discounts would also occur regardless of whether it's called the 10th Anniversary sale, or the Back to School sale, or the Fall sale, or any other name.
So why are so many people hyped as if the 10th Anniversary sale would bring something new to the table like they've never seen on GOG before?
Well then, you're not invited to the party you Debby-downer.