Absolutely. Like I said above, most authors who think they’re going to finish their WIPs are wrong. But I still say that we the reading public ought to treat their crazy, probably-mistaken hope as having more value than our closure. Respecting and protecting that hopefulness is how we increase the number of finished projects we get to enjoy–not all the ones we’d like to see, by a long shot, but more than we’d otherwise get.
For almost any creator, let alone ones doing it as a spare-time creative side gig, there’ll be times where their hope gets awfully fragile. An author who feels forced by their fans’ expectations to make an update during one of those rough stretches has to try to put that unlikely-seeming hope into words–which can easily kill it.
A lot of projects will go through a Schrodinger’s Cat phase where if observed, they’ll probably turn out to be dead…but if they make it through without a wave-function collapse, they may come out of the box alive after all.
So yes, it’s usually a safe assumption that long silence means project death-- and try not to resent the silence, knowing that for some authors it’ll be a precondition for the pleasant surprise of them finishing after all.