Will current hybrids become unsold in several years?

Good evening, I am about to buy a used CUPRA Leon ST Hybrid 1.4l/13kWh with 245hp. I have several viewing dates behind me, but finally found a suitable one where I intended to sign the purchase contract tomorrow. Now today a well-known one who works at the Tüv came to me and advised me on the purchase of a hybrid, since apparently in the next few years (3-4 new battery technologies come out and thus mine a lot of Rkeren has lost value as a general rule and I don’t get it sold again. I’m really unsure now if the purchase is actually the right option. I don’t really want to wait 8-10 months for a new leasing car. Thank you for your help!