You can play the "what if" game until the cows come home, and there would be no end to it. There are no answers. What if Tesla got his ideas from Leprechauns and they repossessed their pot of gold after he died? What if his notes had magical incantations written on them that drove anyone who read them mad, so they had to dump the notes into a cavern? What if Tesla never existed and his whole history was a fictional narrative? What if...? What if...? What if...? As a Devil's Advocate, you have no where to go.

What if he was losing his touch as he became senile, failed to record his ideas---which were of dubious worth---and his "estate" amounted to indecipherable memorabilia that was indeed returned to its rightful owners?

I guess that would put an end to the magical thinking that, somewhere out there, we have the Lost Tesla Patents and Inventions that could lift mankind out of drudgery into a technological paradise of bread and honey. This is just like the Cargo Cults of the Pacific Islanders: "Sometime, somehow, our Ship will come in!" It is childish wish-fulfillment fantasy. The modern embellishment is that Evil Black Hats are preventing the ship from reaching port, or have hijacked the cargo.

If there was any worthwhile technology, it would have emerged. Nothing has. The patents are, by definition and intention, public property. No such thing as a secret patent (or it would be a contradiction in terms, since the whole point of a patent is legal protection by public announcement). Absolutely nothing stopping anyone from picking up where Tesla left off. No one has.