IMO the spindles will never be modern or the way the newel post is made. What else besides the painted rock is going on in the spaces . Post some pics of at least the LR furniture.

I would paint the spindles white and then see. I had a similar staircase and painted handrail and treads black and everything else white.

Creative idea- Painted stair treds by Fox Brothers Painting · More Info

I posted this on the fireplace string as well, paint the mantle black to match. You don't have to replace the spindles either, to get this look ...I think these are iron. My neighbor did her railing and spindles in black and I loved it!

@Patricia Colwell Consulting I have Tao shelf and corner sectional in taupe, tv stand, and Huge white fireplace we just limewashed. I am attaching pictures of both furniture items but not in my living room as everything shifted due to remodeling.
Any other items are inconsequential at this point.

I like @Dawn Martinez idea with a slight change. I would paint just the top of the handrails in black and leave the spindles white. The steps would need to be painted black and white to match and then perhaps add a runner.

@kiffkat, yes I was thinking about that too, keeping the spindles neutral to match the trim; but I can't tell if the trim is cream or white. The risers should absolutely stay white either way, with the stairs painted black to match the railing.

Personally I'm loving the all black for this staircase primarily based upon the fireplace reno they just did (another post) and wanting the space to move toward modern. These spindles aren't modern in shape at all, but the OP said they won't be replacing them. So that pushed me toward the all black.

What you posted looks great too; I do think that look can be transitional but leans traditional, what do you think. (did you see their fireplace?)

@Dawn Martinez Trim is white. I am following @Beth H. advise from my other post and changing light bulbs to something more cool white as they are way too warm/beige right now which makes everything pinkish yellow.

My thought is to paint rails something like dark espresso color and spindles white. Painting steps is not an option right now as sometime in the future (maybe next summer) I want those floors to be sanded and stained different shade,

@Sam K, if the trim is white, and you want the spindles white I'd color match them to the trim. Beth H is right, changing bulbs can make a big difference, bringing in daylight cooler bulbs will allow for better color matching and better answers on houzz...so I've learned ;-)

If you decide to do the railing in dark espresso I'd consider matching the small mantle in that same espresso.

If you're still going with gray walls as you mentioned, remember gray is cool and espresso is warmer than black. (again lighting will make a big difference)

Kiffkat's second photo looks like espresso rails and white spindles, looks nice, but not modern, more traditional/transitional.

Also, the stairs treads can be the same color as the railing and the risers white, even if you change floor color, you'll see on houzz a lot that stairs don't always match the wood floors, they're accents. But wooden stairs can match the hardwoods...so it's personal preference.

Dark handrail, white spindles will work fine as long as the dark color corresponds with the floor stain to be. The dark color with the current floor stain will not look great but if you can live with it for a year, then proceed. Otherwise I would paint it all white. Gl :)

If you are planning to redo your floors in the summer, can you hold off on the stairs? It would be better to match the railing and stair landings after you get your new floor.

@Dawn Martinez. I have a huge fan that is dark brown ( I call it espresso) and I am thinking of making mantle shelf the same “espresso” color so rails would be matching so to speak. Also I don’t hate gray and brown...