Indeed. The Brexiteers surely know this so won't they act to prevent such a long extension? Do they have sufficient power to do so?
(Pardon a Yank's ignorance of British politics.)
Brexiteers are a colorful, disunited bunch. You have some in the ERG, who think no deal Brexit is all rainbows and unicorns (or at least claim that), you have some in Labour who think (or equivalent) Corbyn's idea of a Norway-style Brexit will tear the UK off the EU lobbyists while allowing a development of social Britain along the lines of the Netherlands or Denmark. Then you have those who aren't Brexiteers at all but represent constituencies that voted for Brexit so they feel they must ensure a Brexit to represent their voters.
A no-deal Brexit is favored by the ERG only, the others prefer a different Brexit and they can't agree on which. A hodgepodge mess all around.
Anyway, to answer the question: the long extension throws a spanner in the workings of the ERG vermin, but offers the others an option that is more to their liking. A different Brexit deal, along the lines of what Corbyn suggested (save for the main upsides he promised) is entirely possible, a long extension favors those. It would also be acceptable to those Brexiteers who just support Brexit for the sake of their idiotic constituencies, since another referendum may well change their minds. I see this as a non-zero possibilitiy of happening.
How large is another question altogether. The delay would likely split the Tories asounder. Decent people don't care about that, but Theresa May does and she's in charge.
The odds are "nonzero", that's as far as I'm willing to say right now.
McHrozni