Looking at ARM's results:
http://www.design-reuse.com/news/38504/arm-q3-2015-financial-results.html it does not seem that obvious: Cortex-A only accounts for 17% of the unit shipment, obviously it has a much higher ASP, but it is still a balanced product portfolio, there are many places that are growing faster than the smartphone market is slowing down.
The ASP for ARM is probably increasing as well with the move to ARMv8 and more complex SoCs as well.
To be more on topic, maybe the question you should ask is: what will the consumer devices will look like in 5-10 years?
Microsoft is doing Continuum, and you are getting more and more web based and streaming based devices (20M chromecast sold, that is not insignificant), so there is a good chance the "thin client" model will
finally be used.
Basically the client and the network are now (or will be in 5 years) good enough to provide the user experience people expect, and anything that requires more computing power can be done somewhere else more efficiently.
Will these "thin clients" be laptops, tablets, smartphones, TVs, HDMI dongles, something else... probably a mixture of everything, but the need for big CPUs in these machine is decreasing and will continue.
The only exception to that is gaming, but from the reviews it seems NVIDIA Grid is not too far off already, I can easily imagine that in 5 years this will be a solved issue as well.
I guess the big moment will come with the next gen of consoles:
If they stay on x86, there will be no reason to push all the SW to ARM as there will always be a significant gap in the offering, hence no incentive for anyone to move to ARM.
If they move to ARM, a big chunk of the most demanding SW will have moved to ARM already, getting the few major professional apps (Photoshop and friends) moved over is not such a big hurdle, especially because it would also open the tablet/smartphone to them.
Whether or not you would loose a bit of performance by doing it is not that important, for the users that are performance limited, a cloud based solution powered big a BIG cpu will almost always win.
If you go one step further, you can now have CPUs tailored for hosting specific apps with accelerators tightly coupled (FPGA or ASICs) which will give a massive win, something that is not possible with a consumer grade solution.
Once you get to that point, being x86 or ARM is mostly irrelevant, it will be slightly easier with x86 but you will have to recompile to use these accelerators anyway.
Maybe this will not happen because it is too complex, because consumers are always going to stick to the same "install my apps and run locally" model, but this seems to be where the industry is heading, Intel included (they would not have paid that much for Altera if they only wanted to fill their fabs).