Here's one way to look at what to expect from Beagle.
In the last decade, there have only been 92 forwards who played at least 160 games after the age of 33. (Beagle will turn 33 in October and he’s signed for 328 games.)
Player Season Finder | Hockey-Reference.com
The vast majority of those players were either stars or scoring-line players in their prime. Guys like Jagr or the Sedins, but also guys like David Legwand or Craig Conroy. Those aren't great comparables so put them aside.
If we're solely looking at guys who were career 3rd/4th line players, like Beagle, then the list of guys who aged well basically shrinks to:
Jason Chimera (444 games as a 33+ y/o player)
Dominic Moore (367)
Craig Adams (362)
Jeff Halpern (327)
Jamal Myers (320)
Derek MacKenzie (303)
Vern Fiddler (297)
Chris Neil (295)
Scott Nichol (288)
John Madden (262)
Chris Kelly (242)
Matt Cooke (241)
Matt Hendricks (241)
Eric Boulton (236)
Jarkko Ruutu (233)
Ethan Moreau (218)
Mike Grier (208)
Kris Draper (207)
Jay Pandolfo (193)
Dan Cleary (192)
Eric Belanger (186)
Sami Pahlsson (162)
Only about 22 forwards total across a decade of hockey. I also tried to be generous with comparables here; many of the players on that list were much better in their primes than Beagle ever was (Chimera, Halpern, Draper, Madden, Pandolfo, Pahlsson, etc.)
So judging from recent history, an optimistic projection for Beagle is a late career along the lines of Derek MacKenzie or Dominic Moore or Matt Hendricks or Scott Nichol.
And that's probably closer to a
best-case scenario than a most likely scenario. Even those guys listed are exceptions, not the rule. Most checking-line players just don't play very many games after the age of 33.