Given the advances, how possible is it to use Linux without ever touching the Terminal? Until the answer is "100% possible", it will never be the year of Desktop Linux.
It's also worth noting that desktop computers are dropping in popularity for home users. Gamers will use them for years to come, but the average non-technical home user that just wants a web browser and social media are more likely to opt for a tablet these days. If they REALLY want a keyboard and a larger screen, they'll probably get a laptop.