Stock Shock Lifespan
 

At 50K mi and adding lowering springs how much life do you feel is left in the stockers or would it be wise to change out to Bilsteins now. I would rather not spend for new right now however paying twice for labor while things are apart for springs now may not be the best route.

Opinions will vary, but if it were me I'd replace the OEM dampers now while everything is apart.

I've heard (not my opinion) that shocks should be replaced @50k. I changed them @120k on my Camry, but they were WAY past due at that time (change was too noticeable).

I'd say the same, especially since you are getting lowering springs. Most likely the stock shocks will be worn out way faster using the lowered setup. After all, you will probably get charged the same for labor in changing shocks and springs, or springs alone (your wallet will be lighter though).

Nobody knows, but if you're hunting for improved performance might as well spring for the Bilsteins up front.

If they're not leaking and the ride is not too bad then you probably dont need to change them out. The real question is whether you want to change them out for something better.

Change now at all four corners.

Bingo.
They will work fine for you at 50k. I'm sure they would last another 50k.

But if you want to replace them now, might as well get better than oem.

FWIW mine weren't working fine for me at 40,000 miles. Ride was noticeably different than when new and one of the shocks leaked.

Similar to @Pat , mine are at 40k miles now (and a lot of track days as well) and while they are not leaking, they barely work at all. Almost every bump is a two bounce bump (the whole point of dampers is to prevent the suspension from cycling up and down by absorbing the energy of the springs), im changing them this year, the only reason I havent changed them before is because im all stock suspension wise so Im going to do it all at once.

You should, while at it, get better dampers that would go better with a lowered application (the Bilsteins with shorter body are a good option).

This is sort of one of those questions that really can't receive a yes or no answer but qualifies for a solid maybe. Where and how the car is driven will impact life more than mileage. I personally have had stock (other cars) last for anywhere from 20K to 200K miles. Currently I have almost 100K miles on the stock with RSR lowering springs since mile 1 and they are all still working fine.
Gonna throw in with the "may as well do them while the car is apart" crowd though.

I'm at 82k miles and have had eibach lowering springs since 20k miles and my shocks and struts are working just fine. I try my best to avoid potholes and drive decent roads tho.