But seriously, there's an astronomical # of addresses in IPv6. You're probably right that if we ever exhaust that space, we'll probably be communicating between planets by then.
There is an astronomical number of individual IPv6 addresses, but in most cases that is not really the meaningful number to look at, at least right now. IPv6 is not really supposed to be subnetted beyond /64, so that already slashes the network space quite significantly. ISPs are supposed to hand out full /48s to customers (probably does not apply to consumers though), so there goes another 16 bits. The basic unit that RIRs give to ISPs is a /32 (afaik). Which leaves far less astronomical number of individual networks left. 2^32 - 2^48 is no doubt still a pretty big number, but not really as mindbogglingly humongous as 2^128.