The question was "are they struggling to remain relevant," and the answer to that is a resounding no. Obviously future fortunes can change.
Sure. But in the markets ARM is playing, Intel has never played (whether they wanted to or not). Except for what Apple is doing, ARM has nothing to compete with Intel and AMD in the general-purpose computing market. Maybe this will change with Microsoft defining an ARM Windows platform. But up until now, ARM is too fragmented to be relevant in the traditional PC market. There's no such thing as a generic ARM PC that can run a generic, stock OS. I've never quite understood the love Linux enthusiasts have for ARM because Linux on ARM is, frankly, an awful experience outside of a very few, well-supported SoCs like the Raspberry Pi (which is hardly a PC competitor). RISC V coming on the scene is doing no better in that department.
Intel and AMD's hegemony remains pretty secure. The only ARM computers I would ever consider buying and running Linux on would be from Apple because they've defined a hardware standard in terms of boot environment, device tree, etc.
As for the breakdown of Intel's market, I think servers still make them a lot more money than you suggest. More money per chip than generic PC sales which have slumped for years. Even in PC sales, Intel still holds nearly 80%.