Absolutely nothing.

+ You're in the majority. For example, only ~40% of the global traffic Google receives is over IPv6.

+ There aren't any generally availably internet services.

If you ever find yourself worrying about NATs, reverse NATs, or, generally, exposing things running with a non-internet facing IP addresses to the Internet, it may be time to learn more about IPv6.

Until then, for the use-case you've described, you're good.

For your home there's nothing to lose. IPv4 is just fine.

I'd go even further as to apply this to most small and mid-size businesses.