I own an ecommerce agency (multi platform - mid to large sites) and we talk a LOT about payment gateways with clients and we look at a lot of data - Paypal is added by default on every single store because customers demand it and that isn't changing. In addition Braintree has competitive rates and they are innovating (for a company this size) with Venmo etc. I only see steady, solid growth here.
BNPL (Klarna etc) - have a place on some sites but they are waaaay too expensive for many businesses and we see many clients avoiding now due to high costs. We offer and keep offering other gateways and split test the hell out of everything but Paypal takes the top $$ even with younger demographics. If anyone thinks Shop Pay (basically a rebundled Stripe) / Google / Apple pay / Klarna etc can eat into Paypal they should spend some time talking to the people who accept serious payments online and who spend time split testing this stuff. Paypal is only going up long term.
My advice: buy this one in steps. I do hope it goes down more.
And if Stripe lists - watch that.

$PayPal(PYPL)$ $Apple(AAPL)$ $Alphabet(GOOG)$