I honestly don’t really like it happening at all, but I’ve accepted that it will. I think it’ll reduce the significance of their duel in ANH, but perhaps they’ll spin it in such a way that provides more substance to that or to other moments in the OT. For example, perhaps we’ll see how Ben came to completely lose hope in Vader ever being redeemed (as he says to Luke in ROTJ)?
In Return of the Jedi, Luke asks Vader to come with him, and Vader replies, “Obi-Wan once thought as you do. You don’t know the power of the dark side. I must obey my master.” To me, that plus Obi-Wan describing him as more machine than man, twisted and evil, suggests they must have met at least once where Obi-Wan tries to bring him back and fails.