There's always been a standoff because Usmanov wanted Kroenke's shares and Kroenke wanted Usmanov's. Neither would blink first. And the two now actively dislike each other, meaning that it's personal. So while it's made sense for a few years now that Usmanov should sell his stake and move on (given that he has less shares and therefore no say in the running of Arsenal), he's stubbornly refused to because he doesn't want Kroenke to get hold of the shares. Problem Usmanov has is nobody else wants to buy them because they know Kroenke's endgame and the fact that buying up the shares buys you zero control at Arsenal. So it's been a stalemate for years.
Unless Usmanov is finally letting the grudge go things won't change at Arsenal - and therefore any dream of Usmanov 'officially' throwing his money in Everton's direction will remain purely speculative.