I have done Spritesheet animation in the past with Starling and targeted Flash/Air. When creating the sources I worked with 150 ppi, because not many Monitors on the market will have a higher ppi-value.
Now I am thinking that more and more tablets are almost at print resolution (300 ppi). Does that mean that I pretty much have to double the ppi- value to be on the safe side when using canvas?
Will an ipad air 2 that has 264ppi somehow "blur" Sprites that come from a 150ppi Spritesheet?
I think that dpi is ignored, all images are 72 dpi. The usual approach in Starling is to use an asset manager, that gives back higher resolution versions of the graphics. So, you might have a 1024x1024 spritesheet for non-Retina screens and a 2048x2048 for Retina. The asset manage does the worrying about which one to use, and the rest of the code should stay the same.
You could just try your game and if you can live with it on Retina, don't bother doing anything. If you want to look into it more, do a Google search on starling asset manager retina, there are lots of discussions to read.
On the GSAP forum, people who have to use specific non web safe fonts, are saving their transparent PNG copy images at twice the actual size for retina display, otherwise they are blurry, so a 300x250 is saved as a 600x500 and scaled down to 300x250.