I suspect it will at least be publicly available, although there might be some terms attached (I don't know).
SEVIRI (the current instrument) has data available through the EUMETSAT data store. It was a while since I registered, but it was at least free for personal/educational/research use at that point.
edit to add - the current iamgery is also available here [2]. Excellent if you want some psycadellic composite imagery. Day microphysics is a personal favourite, although I am biased... [3]
> at least free for personal/educational/research use
That's closer to gatekept than open, IMO.