BobW definitely has a point there,
after updating from a A1000 (with sidecar), through a A2000 (with bridgeboard, 8MB, Harddisks and a midi-interface), I spent quite some money on upgrading my A4000. Within 5 years I spent about $5000 on it. (Harddrive, MO-drive, RAM, Maestro-pro Audio card, Cyberstorm MKII with SCSI, SCSI-scanner and ofcourse quite some software). Then I didn't spend much more than $50 a year on it. I was satisfied with the reliability, speed, supported software. I had become a true user, instead of the PC-hardware-buying-junkies all around me.
Only about 2 years ago, I bought my last upgrade. Now I surf on the internet with cable. Seems like one of the last unforfilled desires.
It can play uncompressed audio in studio-quality. So I have no need for MP3 (which it plays fine if I want it to). But might rather copy something uncompressed to Minidisc to listen to in the car.
MP3 as backgroundmusic in nothing for me. I use the radio or play a cd or even a record.
So that only leaves Video something of a last wish. But do I really need it? It's nice, but not a neccesity. If only the demo of frogger could play a little more then 10seconds, I'd be happy with that.
But I've bought some second hand laptop and a Mac for extra fun and networking. I'm switching them over to Ubuntu-linux now. But even though they are 7 to 8 years newer than my A4000, it's such a drag booting them up, waiting endlessly until I can finally use them. Boring, really. Equally on starting programs. The A4000 comes first. It's just so much more efficient. Even with just my 68060/50.
So my advice: Keep your 68k-Amiga and if you want more of the same, but faster. Buy an A1 or Pegasos as a bonus put them in one network.
