Lock ins are only a problem if you sign a contract to get your phone costs subsidised. The solution is not physical sims, its stop buying over priced shiney things with a contract just cuz MaBell will give you a "deal". You can almost always get a better deal yourself if you are willing to look for it.

I pay in a year less then most ppl pay for a month of the same exact service, but instead of paying T-Mobile or Verizon $40 I pay $4 for the same amount of data. Instead of buying the latest phone I get a used one that will get updates for the next 3+ years.

I don't see how apple or Verizon or anyone else could really ever make this setup not work for me unless they lobby congress to destroy MVNOs and used phone resale.