This is vey interesting! I have been thinking how a sensor like this would work on a medium-format
camera or back? I see they now do some kind of multishot with 7 images done at just one shot.
This should be very interesting to many?
I agree with you
That appears to be the Foveon's (X-Trans') strong point: extremely high-fidelity images ... at base ISO.
We really need companies like Sigma who dares to follow different ideas!
We should ll buy one just for support of the different ideas
Again, we agree!
Bernard mentioned some of the limitations ... and really underscored my motive in making this post:
the technology needs support.
Right now, "nobody cares," because Sigma hasn't developed its camera line to compete with Canon and Nikon in the same fashion as, for example, Sony.
The Merrill/Quattro cameras have very little "all around" use, especially in regards to AF as well as performance at ISOs over 800.
However, for
static shots, on a tripod, at Base ISO,
this is where the Foveon shines 
Canon apparently realizes this ... namely, that the X-Trans sensor is better-suited to Base ISO shooting ... which is why their "beyond 100mpx" future sensor size appears to be employing an X-Trans (Foveon-like) technology. Remember, Base ISO is what has kept the Nikon D810 as one of the most popular landscape DSLR of all time ... approaching medium-format-like results, at ISO 64, with an Otus lens. The D810 is still the leader in this regard.
From the cursory reading I've done Foveon sensors, they excel the Bayor sensor at base ISO capability, which is why Sigma Corporation purchased Foveon, Inc.. However, while Sigma is approaching (equalling and, in some cases, even excelling) even the best lenses today ... its overall camera usefulness (Merrill / Quattro) is below those of Canon and Nikon as well as Sony. Sigma just doesn't have the AF camera-crafting acumen of the giants. This is impediment is further exacerbated by the fact Sigma mount has zero support from other lens manufacturers (e.g., Otus, as you suggested).
This is why I believe it would be far more interesting to me if Sony were to purchase this technology than purchasing Nikon. First, I don't think Sony would gain as much by purchasing Nikon (who already uses Sony-owned sensors). Yes, Sony would gain the best primes AF telephotos in the world ... but they'd be securing a redundancy in sensors (they already own them).
However, by purchasing Sigma, Sony would be adding better lens technology than their own as well (as the Sigma Art lenses are most assuredly better than Sony's--as are the Sigma zooms-- as well as Sigma prime super-telephoto lenses). Better still, since Sigma owns Foveon Inc., and since Sony most definitely is in "sensor-company-acquisition mode," Sony would be securing a
double coup in adding Foveon, Inc. to their acquired sensor-company portfolio.
Better still, for you and me, Sony's AF + camera-usefulness technology far exceeds Sigma's, so they would essentially be "picking-up the Foveon ball" and
running with it. Even better, Nikon Corp, who already purchases its sensors from Sony, would now be able to add this Foveon technology to its base-ISO cameras.
Right now, the Foveon sensor is limited by Sigma's own camera technology limitations: its only available in Sigma mount.
But how that would change if Sony got its hands on this Sensor! Not only would Foveon sensor use be expanded to the Sony mounts, but (most likely) through this to other system mounts (Nikon, Olympus, Pentax) via Sony supply.
In closing, if the Canon Rumors are correct, the industry leader, Canon, has already realized this, and is developing its own high-megapix cameras in the X-Trans sensor direction.
Perhaps there will be an eventual bifurcation in sensor technology across all platoforms: Bayer sensors (which perform better at high ISOs) will continue to lead the fast-action/sports/wildlife lower mpx market (like the 1Dx, D5, and A9) ... but where Foveon/X-Trans sensors (which have better base ISO performance) will begin to dominate the Landscape/still market (like the 5D, D810, and A7r), especially as they approach/exceed 100mpx. It was directly stated that X-Trans favors sensors over 100mpx.
