goalies usually age well
This is a common misconception, which is perpetuated in part because the stats of any one particualar goalie tend to bounce around from year to year.
In fact, by the time most goalies gain the full confidence of their teams and break into the NHL, they're quite likely to already be as good as they're ever going to be (or maybe even past their absolute peak). While again this can vary on an individual basis depending on luck, coaching, situation, etc., as a group goalies statistically decline consistently year after year beginning already in their early 20s.
https://hockey-graphs.com...-at-a-goalie-aging-curve/
https://ingoalmag.com/ana...enders-aging-and-the-nhl/
This last season, there were only 6 goalies in the NHL at least 35 years of age who played at least 30 games. Of those goalies (Luongo 39, Anderson 37, Lundqvist 36, Rinne 36, Smith 36, McElhinney 35), only Rinne and McElhinney had save percentages higher than league average (and McElhinney only barely).
I would in fact argue that Rinne was the only NHL goalie above age 33 (Greiss) who had what I would consider to be a genuinely good season, although Fleury (34) might have skirted the boundary between "good" and "above average."
Now granted every goalie is different and sometimes you do get lucky. Roy was still all-world when he retired at 37. Luongo was great (in admittedly a small sample size of work) last year at age 38. Hasek had his last great season at 40 and was still above average at 42.
But I wouldn't exactly count on Bob to maintain an elite standard of playing ability for 8 more years. He would definitely have to beat the odds.