[zellyn]

One big question: will carriers still charge exorbitant per-message fees?

And one huge question: will iOS support RCS?

[bsharitt]

Are there still companies that still charge per message fees?

[gurrone]

Depending on the contract they do. Often enough it's the GSM modem paging someone for alarms that holds a SIM with some old corporate contract that has no flatrate. And you'd violate the contract if you exchange it for some private contract SIM with all inclusive SMS.

[neves]

Sure, specially if you have a prepaid phone (very common in third world countries)

[moreati]

Yes, every mobile phone operator in the UK charges for SMS and MMS if you're PAYG user. Users on contracts typically get 1000s of free SMS per month, but I'm not aware of any contracts that have inclusive MMS.