The absence of conditional call forwarding on T-Mo prepaid plans is a hugely annoying thing. Here's one blog post about why prepaid plans might be less desirable that gets into lots of details.

The magic date when my VZW lockin expires is rapidly approaching and I have no idea what I'm going to do. It looks like our family situation is going to change from how it is now (one LTE phone with a legacy unlimited plan and one crappy feature phone) to something quite different (two smartphones and a tablet, all LTE-capable), making my legacy VZW plan less interesting, never mind that it seems unlikely that there will ever be another Nexus phone on VZW.

In my dream of dreams, Google creates an MVNO where your GVoice number is the only number you have. Do voice-over-WiFi when you can (as with Republic Wireless), and otherwise fall back to GSM with a reasonable price (anything under $50/mo) and they'd kick ass all over.

Sigh.