Would Luke have still been killed by the projection feat in TLJ if he hadn't just reunited himself with the force?
I ask because he had disconnected himself from the force for YEARS, then reconnected with it, then just a few hrs later preformed what is arguably the most advanced force feat in canon.
Would the exertion still have killed Luke if he had never cut himself off from the force in the first place, and was still fully acclimated to it?
Novel and sourcebooks state that Luke cut himself off from the Force as well.
As for the question: the projection works by dumping your own living Force into it. The longer you manifest the projection, and the more 'real' you make it, the more of your living Force is required to sustain it. That's why Luke died -- he basically poured all of his life force into the projection.
So *maybe* Luke could have done the projection feat without dying in the process if he had maintained his connection to the Force over the years, but I doubt it. I don't see why cutting himself off from the Force would've impacted the amount of living Force that he personally contains.