silentpat

This is fantastic - thank you so much!

I second the Klipsch set at Costco and the Wharfedale's, great choices.
 

Well There's powered speakers that dont require an amplifier (because it's inbuilt), and there are unpowered, which do need an amp. There's a ton of options out there depending on what you're looking for, I'll list off some of my favorites (Assuming USD):
 
Powered speakers (self-contained, require no amp)
 
Adam t5-t8 series. High performance Basic black box, smaller sizes are more suited for closer use. Larger speakers will provide more bass, but if you have them too close to a wall It'll be bloated and won't be very well controlled. Pretty flat and neutral overall, t8v has more prominant bass and treble (V shape sound sig)
 
Klipsch the Fives (purchase from Costco for $500-$600). They have tons of connection options including HDMI arc, you can adjust sources on the fly easily. They're pretty flexible and can work backed up to a wall but they again like a little breathing room, and they're quite classy, with a real-wood verneer and nice colorways. Also more of a v shape, It'll be pretty agressive with the bass and treble.
 
Various edifier speakers ($100-$700). Most edifiers at this pricerange are quite solid, they're pretty classy, they perform pretty well, they're pretty flexible.
 
Moving on to unpowered speakers (will require an amp, which I'll discuss later):
 
Kef q150s (On sale for $350). Flexible about placement and where you sit relative to it while listening, It's not the prettiest or best-built speaker in the world, but [imo] damn, does it sound good. Doesn't need much space behind it but it'll reward you in spades if you decide to play around with it to place it right. Mildly pronounced bass. 
 
Wharfedale Diamond 12.0-12.2: Solid performers that emphasise lower midrange, not offensive at all. Well-built, they sound good, they're just overall pretty safe choices. 
 
PSB speakers: Interesting design, Some people quite like them however I haven't tried them myself. Should be flexible about placement, and there's powered variants of them, too. Slight "V" curve. 
 
For amps, I would probably recommend the sabaj a10a. For the price it's super solid, and it'll provide all the power your system needs. Even comes with a remote. Now, this only has RCA in, so you would either have to use that, or get a converter from amazon. Alternatively, you could buy a dac, but one with HDMI inputs or such (That's also decent at it's job, acting as a device that would also improve your sound), could cost a pretty penny. 

If you want greater fidelity or more connection options (If you're just missing anything in general) you can go ahead and list your budget, and if you're okay with actual speakers (which will sound far better unless you're talking about spending cash in the upper hundreds or lower thousands, where soundbars catch up a little). 

Audio products tend to be very "future proof" in terms of raw sound. The sound quality didn't change much from high-end 10 years ago to high-end now from what i understand. The main reason you'd want to upgrade is if you want some sort of surround setup or you need other connectivity options that didn't exist when your other speakers were around.
 
Soundbars can deliver very impressive audio, my Samsung HW-Q80R sure does! But you need to get into a rather high budget when you want them to sound as good as decent speakers. They bring a lot of convenience and the spacial audio is better than a standard 2.1 setup. But the virtual side or surround speakers are still nowhere near a real speaker and the shape of your room can have a big impact to make the virtual speakers more effective or ineffective.
 
All in all i'd happily recommend the HQ-Q80R with it's optional rear sattelite speakers over many conventional surround setups with standalone speakers, but sadly this amazing soundbar is not produced anymore and the successors aren't as good.

unless it's missing things you want / need currently?  Upgrading won't get you a ton.

Tech may have, as in BT connection or HDMI ARC, but speakers.... they'll last decades, if not longer.
 
I would only upgrade if you need different connection types or they just don't give you the sound you want. 
 
There's no reason to replace "outdated" speakers tho.  
 
Still rocking my Mirage home theatre set, my old man still has his Pioneers from Vietnam (yes, the war).  Speakers are one of the "spend as much as you can" on them, as they last.