HA tech has gone mainstream,
I fear X10 is already too far behind to catch up.
I dunno. I have been in X10 since 1978 and HA since 1984 using a Commodore computer that recognized voice commands (sort of) and would control one X10 house code. I wrote articles and reviews for two home automation magazines in the 1990s and had our home written up in the Wall street Journal. In that time I have heard "HA is mainstream" many times. And it ain't there yet.
I thought Z-wave when it first came out would actually bring HA mainstream since soooo many companies signed up for licensing and manufacture of Z-Wave devices. Now I tend to think Z-wave is more dead than X10. Now with everything going WiFi I thought mainstream again is here, as do you. But I still don't see it happening. I hope I am wrong and you are right.
The huge impediment I see now is, even though WiFi is the commonality, protocols are not. Hue doesn't talk to LiFx, which doesn't talk to WeMo which doesn't talk to Nabe, which doesn't talk to ..... And MagicLight, Flux and others went Bluetooth. I suppose there are multi-language hubs out there, but now the problem you note of non-hobbyists not having the knowledge or patience to hack together a multi brand/protocol system comes into play. Lets not mention the feud between Amazon Alexa/Echo and Google Home. They have communality with Phillips Hue, but that's about it.
As far as X10 being too far behind to catch up. I agree. If X10 would act like they are really interested in modernizing the standard, products, and staying in business, they would, at minimum, get their dog WiFi module on the market. After that they should partnership with JV Digital Engineering for a high power repeater design that is simple to install (like Smarthome's clothes dryer plug module). Or design two RF coupled high power PLC amps, again like Smarthome had. Those two things would at least breath some money and hopefully life in to X10.
Like I said, I hope you are right about HA being mainstream. $0.02