Well, the phones and tablets get less underpowered and restrictive each day.

Current phones are way more powerfull than PCs were when Napster was launched. They could easily run something like it today. As they are also powerfull enough to decide what to do with meta tags (or the more modern semantic ones) and to keep several dictionaries of data in place. They just don't do that for marketing reasons.

I also think that things CAN change, but I doubt that change is that inevitable as you say.