We'll see. I cannot fathom why in the hell they would support the system if the Switch takes off like they plan it to. I have a feeling they're reiterating that statement as a fall back in case the Switch doesn't do well.
It'll also be incredibly disappointing if they do this because one of the biggest draws of the Switch is having all the Nintendo games that are going to be made on one system instead of having to buy two. If the Switch does well then the 3DS will be out of the picture by 2018. If not, well, then I guess you can look forward to having to buy games for two separate systems for the foreseeable future.
Also, you're making the assumption that the battery life will be terrible and it very well might be but there is no confirmed reports of anything spec-wise for the Switch. And, let's face it, the DS family hasn't been 'pocket friendly' in a long time. The original DS, DS lite XL, 2DS, 3DSXL, New 3DSXL, and, to an extent, New 3DS are very hulking.