Seeing as how Apple has zero presence in the server/cloud market, how do you figure? Are you hoping they bring back xserve?
Otherwise I don't see how Apple having a custom power-efficient chip in a laptop is going to do anything at all in the server/cloud market?
This is all assuming you're doing anything at all that depends on the ISA and pushing prebuilts of it somewhere. Otherwise it's not like deploying Java, Python, JavaScript, etc... changes at all here.
ARM doesn't have any such benefits. The ISA has minimal impact on power efficiency, performance, or even core counts.
Apple's specific CPU has so far been pretty good, but that isn't the result of running ARM nor does it translate to other ARM CPUs. The specific CPU implementation matters here, not the ISA.
Plus, there have been features of Arm implementations that have clearly given them power efficiency advantage vs x86, big.LITTLE which is now coming to Mac and up until now has not been a feature of x86 implementations.
Removing barriers to developers building software on the desktop for the Arm ISA will have an impact on deployment in the cloud. How much - who knows and it's not measurable, but it will.
Both things can be true though.
If you are developing for web... it depends what you are writing and how you are deploying it, but it probably won't have much impact dependent on your toolchain.