Linux as a platform does not yet exist. "Linux: the platform" is something being worked toward slowly.
"Linux: the kernel" is a technology building block that can be used as part of a "platform." "Android: the platform" is one such construction. "WebOS: the platform" was another. There have been others as well, its clear to me at least that Canonical is moving toward defining a platform where "linux: the kernel" es muy importante.
Can "we" find enough consensus to be able to define "Linux: the platform?"
I'm not sure we can. Platforms are not least common denominator sorts of things. More realistically we are going to see a family of strongly branded platforms, with strong but diverse API policies. Each leveraging "linux: the kernel" and each legitimately being able to claim being a "linux platform" but not necessarily "the linux platform". making linux a very weak platform brand.
We would be better served right now if we admitted that, encouraged the use of distinct platform branding, while simultaneously encouraging and agitating for standardization on plumbing level components which sit above the kernel across those platforms.
The real question is how far up the stack can we get commonality? I think systemd brings enough benefits to the table to be part of the shared stack of platforms which make use of "linux: the kernel". It might be disruptive for some, but significant technology improvements tend to be.