That's impossible to say, exactly. You have this season for sure, probably next season as well, after that is gets iffy - you may have another year or two after that but then again, you may not. What do you think?
Price is your best player by far, without him you're toast, we're all agreed on that I would hope. He should be good for several more years but still, he's 29 right, he may still be playing at this level when he's 34, it's possible but I wouldn't count on it. Weber's 30, he'll likely start to decline well before Price so I'd say he's your biggest concern. To me, trading Subban for Weber moves up the timeline in any case.
JMHO.