Doomed.... can take a very long time.
Yes. Like I said I think X10 is on life support. The X10 problem I see is "newbie frustration" when they buy new CM15A and AHP, when they can get it, with (new) modules and things don't work. X10.com insinuates all one has to do is plug stuff in and instant automation abounds.
Really, this forum is the main way a newbie finds out why modules do not respond. Even the WiKi's do a lot of tip toeing and glossing over.
As Jeff points out, the AGC addition helps with noise problems, But hasn't been the silver bullet, based on forum requests for help. Also leaves phase coupling relativly unaddressed "Why does only one of my three new 'wireless doorbell' chimes work?".
My perception is X10 isn't getting many "new" customers in the automation field (no growth). Hence I think X10 PLC sales is mainly to existing users (the life support).
PLC is saveable, but I just don't see X10 having the development/design resources to pull it off. Besides they would likely have to step on Insteon patents.
Saying this a different way: If X10 were to do an IPO tomorrow, how many of us would be in line to buy stock? $0.02.