Okay, first off, this question assumes I know what contemporary music sounds like, compared to which earlier music would sound dated. I SO don't. I don't have cable TV or listen to the radio, and most musak in stores is oldies--have you ever noticed?
What contemporary music I have heard doesn't sound all that different to me than stuff I listened to back in the '80's. In fact, I've been surprised by how *not* different it is. If someone is doing ground-breaking new sounds out there, I am not aware of who that is.
That said, there is clearly a "sound" to some music genres in particular decades that us unique to that decade. '50's rock sounds very different from 60's rock, which sounds mildly different from 70's rock. Contemporary Hip Hop has clear roots in 80's Rap, but a different sound at the same time. "My music" was late 70's-early '80's Punk and New Wave, and a LOT of that sounds dated now. Especially the peppy, shallow stuff and anything that used a lot of synthesizers.
Queen: hardly sound dated at all, but that's either because their music was purposefully vintage even for the time (e.g., Bohemian Rhapsody), or has become so ubiquitous it can't get dated (e.g., We Will Rock You/We Are the Champions).
Depeche Mode: Early DP *does* sound dated, but see above re: peppy, shallow stuff. Later (late '80's) Depeche Mode doesn't, to my ear.
Ultravox: Okay, yeah, big synthesizer band. But you know, stuff you listened to, like, a MILLION times is so familiar, it's hard to judge.
Roxy Music: Not so much, but they did a lot of deliberately vintage sounds.
Echo and the Bunnymen: They don't to me, but my ear, not the best judge. These guys might fall into the "Extended life via the Goth movement" category.
Elton John: KindOfYeah. But some bands/musicians are so closely equated with a particular decade, they're going to sound dated whether they are or they're not.
Japan: These psuedo-punkers were not mainstream enough to have a trendy sound, and also did a lot of deliberately vintage work. But some songs do sound punky-dated.
New Order: Dance music always sounds dated after ten or fifteen years. It's a thing.
Orchestral Manoeuvres in the Dark: Early OMD falls in the same category as early Depeche Mode. Too trendy for its own good. Later OMD less so, but still.
Peter Gabriel: Most early PG has become classics, too ubiquitous to sound dated (to me). His later pop stuff sounds more dated. Word to the wise: being trendy means being forgotten in five years.
Siouxsie and the Banshees: God, I just can't tell. Maybe?
The Smiths: See above re: too closely associated with their era to ever sound anything *but* dated.
Music I associate with the era and so inevitably sounds dated: Devo, Oingo Boingo, Tears for Fears, U2, X, Yaz, Visage, Thomas Dolby, Spandau Ballet, PIL, Eurhythmics, The Cure, The Clash, Adam and the Ants
Other artists who have continued to be played and so don't sound as dated: Joan Jett, Sisters of Mercy (saved by the Goth movement!)