The article is still quite valid. The sensor prices might have come down a bit further than expected, but a full frame camera still carries a substantial premium, especially when compared to µFT. But more important than the sensor prices are the consequences for the lenses, if you compare the sensor formats. The camera companies have solved the problems with vignetting and soft corners by designing a whole set of new lenses[1]. So a 35mm sensor performs nicely with modern lenses, but those lenses are quite expensive and most importantly, vastly bigger and heavier than their ancestors. So while a 35mm system might provide the maximum quality, for anyone with a budget, both financially and transportation-wise, the µFT system is more in the spirit of analog 35mm format, both size and performance wise, while the digital 35mm cameras drift more into the classic medium format field, in performance but importantly also price and size wise.

[1] Meanwhile Leica managed to bring their digital M cameras to 35mm, getting excellent image quality even in the corners with a mix out of clever sensor design and in-camera post processing.