I can't imagine 3G being switched of in the immediate future. 4G and it's variants are still all relatively new, even with 5G being tested. Not to mention the 2G network has only just been switched off...
As for email providers, what are you after exactly? I use live.com (part of the microsoft network) as my personal email. I've used googles option for business (or my domain) email which worked fine for me - but it depends on what you want to achieve from your email I guess...
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