Yesterday my LBHS sold me a vial of WLP002 that had a date of 5/6/15, for 1/2 price. One yeast calculator didn’t think there would be much to it… another said it should all be dead. Another said, eh… about 19% viability.
I pitched it last night at around 9:30pm into a 1.2 liter starter and threw it on my stir plate. This morning it looked pretty much like most any starter should at about 8 hours. I posted a video of how it looked when I got home… ummm, I’m thinking it’s alive. 
If you don’t count cells you don’t know how much you have.
You will make beer with what that looks like. Probably good beer.
I hope you are right, hoping for good beers 
I’ve often wondered if the viability estimates of some of the online yeast calculators were no too terribly accurate. I feel like they err on the side of caution. You are indeed right though, no way to know for sure unless you count.
I’ve stepped up lots of vials that were over a year past their “best before” dates with little effort. Incredible little buggers…
I’ll echo smokeymcb, I have not met the yeast that does not revive after 5 days on the stir plate, with some DME and yeast nutrient. I’ve revived6 or more 6+ month old yeasts.
Congrats on stepping up your yeast.
I’m glad that you are having some luck with a vial that old, as I have purchased some about that age and been pretty uncertain how they would turn out. I was hesitant, but help out for a better discount than 50% for yeast that was already 2 months past best by date. In the end they worked for me as well, just longer lag times than I had been used to