Well, the *only* scenario wherein this could *theoretically* work out would be if Ragnar somehow traveled to the very tip of southeastern Scandinavia, around the polar circle aka the border to Siberia, and then met some injuns there. I don't really see that happening though, the sagas don't mention it either iirc.
More likely than anything else the fourth season will degenerate into a delusional non-historical made-up liberal spergfest with feminist shieldmaidens, black vikings and whatnot.
Either that or they stay on their mildly pro-white course which seems unlikely since the jews who own the media industry do everything in their power to fight against white norse heritage and culture.