SpamCop is not dead. It is still up and running and the free blocklist is a great part of your anti-spam arsenal. Compare RCVD_IN_BL_SPAMCOP_NET to the other free options using SpamAssassin rule vetting stats and you'll see it's among the top performers. ("S/O" is a measure of relative precision, "SPAM%" is recall.)
Unlike the other DNSBLs, SpamCop also reports spam back to the networks that sent it (with filters to deal with spammer-friendly and negligent network operators, either of which might ignore or even pass on the heads-up to spammers rather than disciplining them).
In particular, SpamCop did well against this Necurs attack but it does not fare as well against hailstorm/snowshoe spam attacks (which IP reputation doesn't help combat). IP-based DNSBLs aren't anywhere near as effective today as they were ten years ago, but they're still quite worthwhile. That said, you're right in that the best ones cost money.
I feel happy, oh so happy. I don't want to go on the cart.