The pricing level for the ARM instances should be interesting. If Amazon prices them well below their Intel and AMD instance types, they could really drive adoption and lock-in.
Adoption? Sure.
Lock-in? Umm...
Most servers run Linux, and most software on Linux is distributed as source. The same reason that people can easily move to ARM - they can just recompile/download software for the correct architecture and everything mostly works - is the same reason they can leave easily.
All the other AWS proprietary APIs: sure. It'd take a stupendous amount of work for Netflix to migrate away from AWS. But running on ARM isn't really part of that.
Clearly you aren't purchasing much software. If you're one of the (majority of) large software companies that use precompiled binaries from vendors for any of the components in your systems, you're at the mercy of which architectures your vendor(s) support.
From the software that runs for hours to compile a model, the software that calculates results, to the interactive analysis software that needs to load GBs of data.
The whole reason to run these things on a server farm is that you need large and fast machines that are better shared to make sure they get optimal use of the machine and of the license pool.
The whole point is that the hardware becomes as flexible as the software, spin up, spin down, blow it away and deploy a fresh instance if something goes wrong.
I can't see many people trying to do that with proprietary licensing?
Being distributed as source code does not mean the source code is not architecture-specific. A lot of software has SIMD-optimized code paths, and it's common for these SIMD code paths to target SSE2 as the least common denominator (since AMD included SSE2 as part of the baseline of its 64-bit evolution of Intel's 32-bit architecture, every 64-bit AMD or Intel CPU on the market will have at least SSE2), so they have to be ported to NEON. And that's before considering things like JIT or FFI code.