>>17674916
>Why?
No proof of it. At best just circumstantial evidence.
>3 centuries at most
Depends on whose dating you go by. Fatyanovo was primarily middle bronze age culture (3rd millennium bc) while Netted Ware was late bronze age (2nd millennium bc). They both spanned wide areas and obviously did not begin and end at once everywhere.
>who replaced Abashevo?
Other indo-iranian cultures. Primarily srubnaya.
>They were descendants of NWC. Material culture is inherited from NWC
Ananyino occupied the eastern end of european russia, stretching from urals to volga. They do not descend from NWC, but from local cultures that preceded them, with migrations from east urals bringing uralic language, culture and genetic component to this region.
>>17674963
NWC developed from local groups. Likely baltic cwc mixed with neolithic remnants of volosovo and pit-comb ware cultures. There's nothing that suggests that these were euroasiatic finno-ugrians. In fact, the only samples associated with this culture that we have are from the baltics and they're typical cwc-like individuals with no eastern admixture or y-dna.

Seima-Turbino was an ancient trade route stretching from eastern europe to eastern siberia. It wasn't a culture of any specific people. What we find at ST sites deep in western siberia is that they were already dominated by indo-iranian steppe people at the earliest stages of this cultural phenomenon, so we can safely rule out any sort of bronze age invasion of europe by altaic or siberian groups via the ST routes. In fact, the opposite happened, and after ST phenomenon we see rapid spread of indo-iranians all over siberia and central asia. Furthermore, proto-uralic was hunter-gatherer language. They were unfamiliar with metallurgy, agriculture, animal husbandry, equestrianism, chariots, wagons etc. Therefore, uralic speakers cannot be associated with ST, and NWC with uralic.