A 6 season arc was laudably ambitious but there just hasn't been the depth and tension to sustain the interest past this third and (most likely) final season. "Lost", to which it is frequently compared, had a similarly beige lead male protagonist but set up many compelling mystery strands even in the first few episodes, significantly helped by a variety of contexts in flashback sequences and by a wider range of characters, each of whom had their time in the spotlight. But the mysteries wouldn't have been enough by themselves, the momentum was kept up by intriguing and well-written heroes, villains and those still to choose sides. Manifest has certainly had its moments but increasingly finds itself in soap territory and the mystery is too narrow to allow substantial progressive revelation and to keep the viewer engaged. The audience aren't fools - if you state it's a 6 season arc based around one mystery event, it's pretty obvious that seasons 2-5 can be skipped. Padding out the narrative with one too many character allegiance swings doesn't help (and the less said about Angelina's story arc the better...).
Judging by these three seasons, there is probably ample scope to condense the remaining three seasons into one and thereby end up with a punchy finale. I genuinely hope this happens and there's an opportunity to conclude what has been an interesting story.
