The problem with Google's Hangouts/SMS integration
So Hangouts will replace the messaging app in the next version of Android, and it seems that the Messaging app will remain in ASOP but not be included with the Nexus 5.
To me it seems like there is a massive problem with this. Unlike Apple, which integrated iMessages into the SMS app, Google are doing it the other way around. This seems bad for several reasons.
Firstly, the vast majority of Android users probably have no idea what Hangouts are. When they want to send a message they will naturally go to the Messaging app. To change it to Hangouts I think will annoy and confuse (many) people. I think this is just one reason that many OEMs won't bother to include Hangouts by default, and will continue to include the Messaging app preinstalled on devices.
Secondly, and more importantly. Samsung phones in particular (and we all know they are the biggest OEM by far), are never going to ship with Hangouts preinstalled.
They already have their own messaging service called ChatON, which is competing with Hangouts, Whatsapp, Line etc. and is even available on more platforms than Hangouts. I would also hazard a guess that as it's shipped on Samsung devices by default it's far more popular than Hangouts.
So what possible benefit would they have to include Hangouts by default? None whatsoever. In fact, I think it is more likely that they will actually just integrate SMS and ChatON into a single app for the next Galaxy S5 or whatever.
In conclusion I think that Hangouts will remain a flop, even with SMS integration. It will only be shipped by default on Nexus devices and a few choice OEMS such as Motorola, and it will remain with a small user base - only used by the nerds/ tech fanboys etc.
Update: Apparently every OEM has to include Hangouts. Therefore my argument is completely flawed/pointless.