iTunes saying bye-bye

Nothing. You will still have it and be able to listen to it. Apple is not closing the iTunes Store. They have announced that they will be replacing the iTunes application on the Mac with 3 separate applications with similar functionality this Fall. There has been no announcement that they are replacing the iTunes application on Windows. See the following from https://support.apple.com/en-us/HT210200

The iTunes Store will still be available to buy music on Mac, iOS, PC, and Apple TV.

I haven't seen any official announcement but strongly suspect that you will continue to use the version of iTunes that you have.

Similarly, I still have and am using without any problems, a mid 2007 iMac that can no longer be updated to current Mac OS. My last and final resting place is El Capitan, 10.11.6 (with occasional security updates). What will happen to my iTunes? Will I get the “new” split version? I don’t have the budget nor intention of buying a new Mac, yet.