I assume not, but hear me out...
.
...it is very odd that Shapeshifter, a Ranger Archetype, forces you to specifically take the natural weapons combat style in the archetype, yet none of Animal forms give any natural attacks...so you essentially have to be a race that has them already. Basically you are forced to take a weapon style you will never use, unless you have nat attacks inherently.
So it would reason that a Skinwalker using the bestial form would take the bite or claw, and therefore benefit from the forced combat style...
But if you cannot take both forms simultaneously, then in order to get that +4 to your Strength with Aspect of The Bear, you would have to not be in the Bestial form?
if that is the case, then Shpeshifter only works with races that have permanent natural attacks...and there are not many, and my idea for a character I lovingly refer to as Skinwalker, Texas Ranger is shot to hell.