I can't find any concrete proof of it?
Just hype machines going off full throttle?!
There isn't anything formal yet that points to that. It is in peoples' opinion that Apple will like Tesla buy BTC but as far as that goes that's speculation. It would make sense for this to happen, though, I do not know when this will happen.
It could be in the next few weeks but it could also be several years from now. What's conclusive is that large companies like Tesla will think hard about why Tesla did what they did and if and when they should follow suit.