The Alienware Alpha is a great piece of kit if you're in the market for a PC masquerading as a console. Alienware jumped the gun last year when they released their vision for the living room PC: it looked like what a Steam Machine would be but, critically, it wasn't a Steam Machine. While it booted into Steam Big Picture – via Alienware's own stripped back UI – it didn't run on SteamOS, nor did it ship with a Steam Controller.
That's changing on November 10 in North America, but during an interview at PAX, Alienware director of product planning Joe Olmsted told me the SteamOS iteration of the Alpha will get its Australian launch in Q1 2016 (that's within the first three months of the year). He couldn't offer a more specific date because “Valve is working through their regulatory approvals for having a wireless device in Australia".
That wireless device is the Steam Controller, which will ship with the Alpha. Olmsted couldn't say whether the pricing structure would be similar to the original Alpha due to currency fluctuations, but the product does sound more in line with Valve's vision for a Steam Machine. "The SteamOS is a console OS one-hundred percent. We did a great job with the [original Alpha] UI but you’re still using Windows, which needs a keyboard and mouse from time to time," Olmsted said. "But Valve is absolutely committed to making SteamOS controller only."
As for the box itself, it will remain mostly upgradeable, though the GPU will be soldered in. That's unlikely to bother the Steam Machine target market, and by necessity it's probably not going to change any time soon.
"We’re working on the next generation Steam Machine already," Olmsted admitted when I asked if they hoped to make the GPU modular one day. "The GPU is an important part but it’s also the largest footprint. I can make it upgradeable if I make it a PC."
So there's your answer: if you want a machine with an upgradeable GPU, get a PC, not a Steam Machine.