I was told "lifetime powertrain" but no specifics around having service done at the dealer. Let's think this thru:
-Where service is done is probably not going to be a valid defense for the dealer to escape a warranty claim. For a dealer or Toyota to deny a warranty claim, there would need to be proof that either negligence thru lack of maintenance or improper maintenance/service/modification caused the failure. Enough people have gone thru this with the original warranty. Same argument applies. At this point, the warranty is a selling point for dealer service.
-The manufacturer is under no obligation to source replacement powertrain parts outside of a certain period. Last I heard this was the original warranty period after the last vehicle is sold, so estimate 5 years after the last 3rd gen. You can bet Toyota's lawyers have written some fine print to cover this. Emissions control warranty is 8 years, so if the PCM, or anything ignition, mixture, fuel delivery, or exhaust fails, you may get lucky.
-A warranty is going to cover defects, not failures due to fair wear & tear. As any vehicle ages, it becomes harder and harder to prove that any failure was due to a defect, and not age of the vehicle. These details don't come up on dealer web sites, but during the transaction when you're at the dealer for several hours signing reams of carbon paper laden agreements.
