I truly believe van will be back in some capacity, whether it be some more intimate acoustic sessions, an album or touring. The reason for this is simple; He will feel hard done by for the 4th album not releasing. It's no secret that he has let the fans down with the numerous cancellations, however he was also let down by the record label for not releasing the 4th album (he may also have some part to this due to this behaviour BUT that does not mean that he will still feel some type of way about it). Take halsey for example, her record label wouldn't let her release any music! That album was going to be an attempt to revive his career after the balance fell short at reaching the same heights the previous two did.
With this in mind, looking at it from an outside perspective his long awaited return did not even get a chance to get going. Additionally, it's also no secret van has always had his family as support, as noted in billys interviews where he stated that they would chip in and help finance/accomodate travel for their early gigs. This is also highlighted in the song "conversation" which he also stated in an interview was about his father. If you were a father seeing your son going through such a situation, how would you act, what advice would you give? Would you really let your son give up on his dream? Van will have to overcome some serious obstacles of course but i do truly believe in him and his family.
Let's also not forget the situation is no where near as bad as it could be. Take Liam Gallagher for example, his voice was absolutely shot to bits after years of drug abuse and god knows what else. And all it took to get the ball rolling was a drunk acoustic session in a pub showcasing a song he made. Van's voice is still fine, and this experience that Van is going through will mostly likely be the catalyst for his new music.
If you've played guitar before or made music you will understand that van will ALWAYS be reminded of what he was whenever he looks at a guitar, it will never leave him. If he hasn't already, then at some point he will be strumming away at some chords and putting together words over a choiced melody. I do expect whatever comes next to be more intimate, but there is no way he walks away for good. Just be patient :)