Depends on your definition. I wouldn't count this sale as any more than a named Weekly sale. Less than 100 titles in the sale.
Considering that there's also a Polish Developer Sale taking place on STEAM, maybe this is the hallmark for another recurring sale. I never realized there were so many high quality Polish made games, but it's great that they are so proud about their work, that they've created a seasonal sale to inform everybody about it. Keep it up Poland!
1) Probably still be a pre-Turkey/Black Friday Fall Sale which probably will start next week.
2) Expect a Black Friday sale. If we have a sizable Fall Sale then this might be more of a slightly larger Weekend Sale.
3) Then the Winter Sale which will be before Christmas and be the biggest of the bunch. Starting 1st or 2nd week of December.
4) Then a Holiday/New Years sale. Again, probably a slightly larger Weekend sale.
Nice prediction, but it feels kind of cluttered. I'd expect only a Thanksgiving sale(probably Piñata styled), Winter Sale, and a smaller weekly&weekend sized sale for New Year's.