The phrase 'has been fading away' is correct and usable in written English.
You can use it when referring to something that has been gradually diminishing or losing relevance over time. For example: “The popularity of cassette tapes has been fading away in recent years.”.
Jane Melvin, 55, said she has typically voted Republican in the past and still yearned for a version of the party that has been fading away.
Since iPLON started to specialize in photovoltaic panels its engagement with Infranet Partners has been fading away, essentially because technical problems repeat themselves at each new installation so peers are less needed for help.
As Nokia has put more effort into a fightback strategy based around Windows Phone-Lumia devices and lower-cost handsets made on its S40 proprietary OS (namely the Asha line), Symbian has been fading away — as I pointed out the other day, eerily represented by a fading logo on its website, which is now maintained by Accenture as part of an outsourcing/sales deal.
This is due to many national factors (see below), the most important local issue being that the earlier fairly well-established sharing of joint and individual competences (see Sotarauta and Mustikkamäki 2015) has been fading away as the universities have been struggling with the many internal issues related to founding a joint institute between two individual universities.
Traditions, language, voices and color of Spanish Jews have been fading away as their numbers are decreasing with migrations and deaths.
A recent analysis of census data by sociologists Sean Reardon of Stanford and Kendra Bischoff of Cornell highlighted how middle-income neighborhoods have been fading away as more people live in areas that are either poor or affluent.
The foreign influence, the interdependence with the United States -- and, most significantly, Mr. Fox's defeat last year of the sclerotic Democratic Revolutionary Party, which had ruled for 71 years, meant that the old soldiers who ran Mexico into something resembling the Great Depression have been fading away.
