Nintendo revealed that they are releasing an updated version of their regular Nintendo Switch soon. The only mentioned differences are the improved battery life when compared to the original model of the Switch. That is it. There are no other differences mentioned.
The good news is that the battery life upgrades are not insignificant. At present, Nintendo says that the current Switch (HAC-001) has between 2.5 to 6.5 hours of battery life, depending on what you're playing. The new model (HAC-001(-01)) will have 4.5 to 9 hours of battery life. Nintendo provides the example of The Legend of Zelda: Breath of the Wild. On the current Switch, you can play for about 3 hours on the battery. On the new model, the battery will last closer to 5.5 hours.
That's a significant improvement there. The changes to the battery life were shared via Nintendo Japan's website. It's also known that this updated Switch model will not be priced any differently than what the current price is for the Nintendo Switch. That means the price should remain right around the $300 (USD) mark.
Just because some changes weren't announced doesn't mean there aren't other changes included. The better battery life has to come from somewhere. That somewhere may actually come from a more efficient CPU, more efficient storage, and an improved GPU. Nintendo had filed a Class II Permission Change with the FCC around the same time that they announced the cheaper, portable only Nintendo Switch Lite. You can actually see the Switch Lite's estimated battery life on the right in the image seen above. These upgrades may not necessarily produce better framerates, but thanks to advances in technology they could be what is producing the better battery life.
Short of Nintendo announcing these hardware revisions are in this updated Switch model, we may just have to wait for a third party to do a hardware breakdown to find out for sure.
cikame The new Tegra chips have been the rumor indeed. If that is what's happening here, I imagine Nintendo won't outright say it to the public because that would, more than likely, cause some confusion with consumers. Or people getting a Switch now thinking it's "not as powerful" as this upcoming revision will get upset or something. It's just easier to say it has better battery life and leave it at that.