Its not a major change, but it does make the sale a lot more valuable for customers, and it allows us to build sale tools that highlight and recommend products all sale long, instead of just during front page features.
It is a major change. Essentially increasing the length that products are on sale will encourage less deep discounts and just a slightly lower price. There is also no reason for me to return to the store after one day. All the curiosity and excitement pretty much disappears without dailys, community choice and flash sales. Even putting out some sort of game to make the store more interesting or improving discovery will still make it a dull affair with higher than usual sale prices.
I'd also be somewhat sure that this applies to the holiday sale, since usually both prices carry over but were expanded to more games / different featured titles and thus varied pricing between sales and through each day.