IQ Online speculates that home automation will see an overall rise by 2011. DIY home automation is seen as a growth area, where pre-installed systems are likely to stall. The report is here: Home Automation To See Healthy Growth - IQ Online.

However, their notion of "standards-based" home automation shouldn't be confused with an open, documented protocol. Instead, they are licensed, controlled implementations. For that reason, I don't see Z-Wave or ZigBee becoming that which causes the tipping point.