You probably don't need to put a warning on an IPv6 user's talk page (like 2601:586:C602:B480:3905:DAF2:CEAD:B07, as opposed to IPv4, which looks like 192.168.123.45) when reverting them. Unless you see that they have made multiple contributions over more than a day from the same address, it's safe to assume that they will never see your message.
This is because the nature of IPv6 is such that the address changes routinely. For mobiles, this is especially true (e.g., Verizon Wireless changes with each connection, which can be on every edit, even just seconds apart).
Even on a fixed line (like a home cable or fiber connection), the subscriber is typically allocated at least a "/64" range, which means the top half of the address (the first four 4-character groups) might stay the same, but the bottom half (the last four groups) will change often.
Wikipedia does not have a way of grouping messages together by range; a user or user talk page is associated with only a single address. So, the likelihood of the same user (or anyone, really) getting assigned the same IPv6 address again is fairly low.