Back in the older days of pop music, there was always a power ballad.
A power ballad is a slow soft song from a hard rock or heavy metal band.
It's not that these aren't around anymore, they just don't get any airplay on pop music channels/stations, which have gone over to dancing routines then later either white guys with guitars or twerking white chicks. Or RnB/HipHop. Or basically don't listen to US playlists - go to Europe (a couple below are from the US but they're probably better known in Europe).
Nightwish - Sleeping Sun
Nightwish - Eva
Nightwish - Creek Mary's Blood (A little bit faster and harder at the end)
Nightwish - Ever Dream (a little fast on some parts that are interspersed rather than towards the end, but this is the song that is likely in every headbanger's "feeling a little emo because I miss her" playlist)
Nightwish - Slow, Love, Slow (more ballad than power, and very jazzy but by a power metal band nonetheless)
Nightwish - White Night Fantasy
Epica - Falsches Spiel
Epica - Run For A Fall (Falsches Spiel), Piano and Quartet
Epica - Chasing the Dragon
After Forever - Imperfect Tenses
After Forever - Who Wants to Live Forever (Queen Cover)
Michael Kiske and Amanda Somerville - Silence
Kamelot - The Haunting (Somewhere in Time) (another not too fast, not too hard-hitting metal love song; plus, there's a redhead singing "like ice on a lake of tears I'll take you through...")
Kamelot - Abandoned
Kamelot - Don't You Cry
Visions of Atlantis - Return to You
Here's one for you...." Always Somewhere " by the Scorpions. Apologies cant link!
If there's a real "decline" to power ballads, it would be in the Philippines. Why? Apart from my own playlist I hear the Scorpions more in strip joints. So much so that when we hear it elsewhere we start joking about what the dancer is doing at certain parts of the song. And when I dated someone from a sociology class and I was humming it she thought I recently was in one. Hell, even my friends who listen to hiphop know the song all because of the strippers dancing to it.
That said, I like how this version of Still Loving You added more power and less ballad.