£15k $22k to spend on speakers...but which?

With that front end I'd suggest used Rockport Altria/Avior, Magico S3 or 5 (but Q3 should one appear at the right price easily bests them), or Focal Utopia Scala.
Can't really go wrong with any unless you've a tiny room?
All are a significant step up from Olympica/Sopra level. For what it's worth adding subs is a whole level of complexity and room thing compared to simply getting your speakers right and with any of the above quite unnecessary.

In januari the new Monitor Audio Platinum series will come
out. The Pl-500 is one I would put on my list if I were
you.

The price in Europe will be 20.000 euro. I think it will
be between 20.000 en 22000 dollar in the U.S.

It is a 1.8m tall speaker what has 3 separate parts. It
will not be a wide and deep speaker. It weighs 120 kilo.
It is a 3-way D'apolito system with 4x 20cm low freq, 2
midd drivers and the new 100khz ribbon tweeter. This one
is wider and bigger than the one who is used at this
moment. It will create an even wider and deeper stage.

I am sure it will be the marktleader in a 3 dimensional
holographic stage. They use a new way of connecting the
low freq. drivers more from the middle. This creates a
superior timing. The ceramic with aluminum drivers will be
the benchmark in response and timing as well.

The front side is with new high quality leather. It is a
lot more smooth compared to the Platinum at this moment.

Internal wiring will be 100% silver and they use the best
and most expensive WBT speaker terminals.

I have a client who owns the Wilson Audio Sasha and he uses the AR 100SE for power. This is not able to create a 3 dimensional stage with the Wilson. Beside this the controle and dynamics are very limited. We will sell his speakers and also his power amp.

Like choosing between 4 types of cheese whiz, consider finding some Vitavox horns.

Acoustic Zen Creschendos are a relatively easy load and may also be worth considering given your criteria.