I'm surprised this new blitzcrank chroma will be 1350 rp

A Chroma is, by modern standards, a skin which only features a new texture for an existing skin's mesh (model).

This means, no change of model (mesh), VFX, SFX, etc.

-_-

The upcoming Blitzcrank skins, Lancer Paragon and Lancer Rogue, are different in their models (as you can see from the concept art and splash), they have different recall animations (as noted in the article) and their VFX (as noted in the article & can be seen presumably in the splash as well). Moreover, I bet that the SFX is at least slightly different, too, but that's besides the point.

This goes way beyond the definition of a Chroma, even if you can't see it with your own eyes or choose not to believe that the two models are in fact different.

Now, the amount of features the two skins will have will decide if they're truly worth 1350 RP each (new SFX for example), but, again, they're at the very least NOT Chromas.

-_-

For easy references, here is the full article with the splash, concept art and all that:

https://nexus.leagueoflegends.com/en-us/2017/10/dev-doubling-up-on-blitzs-hook/

it isn't a chroma, it are 2 skins.