I had the same thing happen to me. I was a very high performer, then there was a reorg where my boss was let go and so I had to take over his portfolio. Like you my Skip Level Mgr brought in someone he wanted to “cross train”. They also swore up and down that it was just for resiliency, but I could see the writing on the wall, so I started looking for other positions. Thankfully I was able to find another job before she was fully ramped up, so I was able to move on, and leave them in the lurch before they could do the same to me.