When will XPM block be halved?

[hl5460]

Current difficulty is 7.97, and block dropped to less than 16 in merely a week. Looks like we don't have to wait 4 years for XPM to halve.

[AgentME]

The difficulty would have to get to 10 for the block reward to be 10. The block reward is 999/(difficulty^2). The difficulty isn't going to increase at a constant rate so that's probably a long way off.