What hosted products has Apple dropped? iCloud might stop supporting old devices but that doesn’t stop you from keeping the data on device or accessing via a new device.
Apple is a bit of a weird case because historically they've been a hardware company first and have done very little in the way of consumer services. But they're just as happy as to kill off consumer products if they want to; they just have a more limited selection to start from (which is itself another layer to the "problem" of trying to use them as a replacement - you can't rely on a product they don't offer).
Apple's problem is they'll often leave products to be stagnant. Existing, but on life support. Like basically all their Mac Apps. A lot of hardware products like this as well, like HomePods.
They have a raft of iOS apps that seemingly come out of hackathon projects that they release, never update, and then maybe quietly kill off. I thought they killed Clips, but it's still hanging out there...
RIP Apple Ping.
It met the same fate as Facebook Ping.