They are competitive but they still trail behind Nikon (D850) and Sony.
They really don't trail behind on ISO. FF sensors are almost all within a fraction of a stop of each other, and there are examples of Canon models being better than Sony models. To give an example, the 'old and busted' 6D2 sensor is much better at high ISO than the 'new hotness' A72 sensor, and they were contemporaries. It's also pretty close to the A73 sensor which is much newer. Another example: people assume every Sony sensor has higher DR than every Canon sensor, but the 5D4 sensor actually out performs several of the A7 bodies that have shipped. (The current 3rd gen matches the D8x0's.)
On DR the difference between the 5D IV and D8x0/A73 generation is pretty small. From a practical standpoint it's a little bit of NR in post. The main "problem" for stills shooters at the moment is that with Canon you can choose high MP (5Ds/sr) or high DR (5D4), but not both. (Though 30 MP is nothing to sneeze at.)
Canon also trail in multiple area such eyeAF, 4K, video features, no IBIS.
With the exception of IBIS, that all comes down to readout speeds. I don't know if they need further fab improvements, if their engineers are struggling with the required circuitry, or if accountants are really forcing them to use a lower cost/larger feature fab line to make money. But they absolutely have to overcome that hurdle. Yes, there are other important things like color, ergonomics, and weather sealing/durability. Yes, they dominate on lenses. Yes, they continue to hold the #1 market position. But they can't hold off the competition forever with poor sensor readout speeds.
Incidentally, it dawned on me that Sony is at the limits of their readout speeds in some respects. Otherwise there wouldn't be a 1.2x crop at 4k30p on the A73. We are asking for
state of the art features here, and Canon doesn't have to be
that far behind at the circuit level to make impossible the things we want like FF 4k.
I wonder if Canon will improve upon those in their EOS R Pro or competitions will make up on the area of deficiency that Canon excel (ergonomic, touch screen menu, etc). Interesting time ahead.
In theory, now that Sony has solid AF, they should be able to solve all outstanding complaints in one generation. How hard is it to adjust ergonomics and a touch screen?
In practice their engineers just don't get it when it comes to certain things, so I don't know if they'll ever be solved. Canon has always been a photography company so their engineers get it. Sony is what you get when an engineer who is not a photographer surveys photographers and designs a camera. Canon is what you get when a photographer designs a camera.
I have no idea what's holding Canon up on the hardware side so it's hard to say how long it will take them to overcome it. The interview with Canon execs and the RF lens announcements leads me to think (hope?) that they're only a year out (or less) from their next generation sensors.
FWIW, thinking about chip wars over the decades (CPUs and GPUs), it often seems like one company is 'down and out' for a few years, only to come back and leapfrog the competition. Canon could upgrade their fabs and next thing you know 4k120p full width FF readout. You never know.