Yes it is the defacto standard, but just trying to point out...

Yes it is the defacto standard, but just trying to point out that there is ultimately not really a PCB that cannot be designed in free KiCAD and that requires Altium instead. The benefits of AD are usability, productivity, and industry acceptance.
The OP asked about competition, and KiCAD is becoming serious competition at the low to mid end of the market.
Eagle was defacto standard in the hobbyist market but it's fallen by the wayside to be replaced by KiCAD. And Altium's low end offerings Circuit Studio & Circuit Maker have also been beaten out by KiCAD now (not that they had any major presence to begin with).
What this means is that Altium is gone in the low end of the market, has competition from a free tool in the low-mid end, and must push further higher end in order to maintain seats. That means KiCAD (and there are a few other paid tools as well) will be taking seats away from Altium in the l long term. So when a new company comes along that needs to design a PCB for their widget, do they spend $8k + a few $k per year maintenance on Altium, or do they use the free KiCAD? With KiCAD now the defacto standard in the low end and open source hardware market there are more and more new engineers that will be trained on KiCAD as the years go on.
If the push to 50,000 seats took 30 years, the push to 100,000 seats may just be a pipe dream.
Remember, a good lot of those existing and new seats don't need the capability that Altium offers.
And if the seat growth slows down because of competition from a free competitor, that will result in an ever increasing seat price to maintain revenue, and that's an upward spiral but not in a good way.
I've been using Altium since it was called Protel Autotrax for DOS.