I think reading all information FD are mostly worried about running support costs for Linux. For that, SteamOS is a match for them - if they ever decide to bite the bullet and do that.
SteamOS is also good because Valve have said they won't force everyone to use Steam. It will be just a reference platform to develop against. You will be expect certain level of OpenGL support there. You will be able to expect certain support for HOTAS and joysticks there.
So for me personally ED on Linux is a long game - I don't expect it to tarrive sooner than in a year's time (if ever).
I feel like a broken record...
As for support, I can understand from a business perspective why they'd be concerned about linux support costs, but if they're truely purely business people who only care about profit, then won't they be pleasantly surprised when they discover just how active us Linux players would be supporting each other instead of pestering them, and just how succinct their bug reports from the linux community will be!
This extends to installing Elite: Dangerous on new distros and feeding input back to FD on how to make their release easier to upgrade and distribute in the future (assuming they don't go the Steam(-only) route.) Hell, I'm sure they could find ways to lower material support costs further by simply working out getting resources from Valve to help them! That is something they could prepare for now, with the Windows and Mac versions in Steam, and leverage that experience if (and sadly not when) they release a Linux version on Steam.
Of course, if they don't partner with Valve, that doesn't matter much either, as it remains that they don't need to target more than one contemporary linux distro, and the players themselves will generate all the self-support we need to shoehorn it into other distros.
It's a mistake to believe being on only one Linux distro or another has you Locked In(tm) to that distro, as would be the case between commercially generated OSes. Linux is a movement, it's not a product. RedHat and SuSE and Canonical could catch fire and burn to the ground today, and ALL of linux's code (and all those distros) will still be out there, free as you or I (unless you're reading this from an oppressive regime, i guess) to continue being hacked on.
The bottom line is, many people misunderstand this, and will call me mistaken, but the fact is, if it works on one Linux distro, it (can be made to) works on all the rest of them (within the same CPU architecture). BECAUSE it's an open platform, any contemporary distro uses all the libraries and programs from all the OTHER distributions, with no thought to Profit Motive(tm) because, again, Linux is a movement -before- it's a product.
And, again, for those that will certainly jump on my case for saying "if it works on one (x86_64) linux distro, then it works on all (x86_64) linux distros", I point you, yes, to the Steam client. Valve -only- packages it for Ubuntu, and nobody has the source code to Steam BUT Valve.. So why can I install it on every other contemporary distro, and in many cases from other distro's native repositories? For example, i have Steam installed on Debian and Fedora.. HOW DAT WORK?!
Lord knows Mac support is going to be expensive enough for FD! Mac users by and large are Customers(tm), not hackers, and have no access to their underlying OS (well, moreso than windozers, but few and far between are Mac users who know what launchd is or what Terminal.app is for), and will come crying to mommy when something's not working right. Not having experience with Linux gamers and the perception that Linux Is Hard(tm) (thought it's not), I can understand why people (inside and out of FD) would imagine it would be the same or worse to support a Linux port.
This is why I've said before; I'm hoping FD isn't too turned off by the drastically smaller slice of money pie and comparably large support load which will come from a Macintosh port. If they're discouraged by the ratio of money to headache that Mac players bring them, they may make the misguided assumption that Linux0rz will some how be as bad or worse! And the Mac community isn't exactly a cohesive beast, I can't just say "don't mess it up for everyone else!", because there's no point. Mac users only have corporate recourses to solve problems, it gives people a tunnel vision Linux users don't have.
TL;DR - My point is, Valve didn't package Steam for Debian and Fedora (and Arch, and Mint, and SuSE, and CentOS, and the myraid of other distros steam is on), Valve packages Steam for Ubuntu. The COMMUNITY of GAMERS packages AND MAINTAINS Steam for the rest of the distros, and they do it without Steam's source code, without complicated binary relinking, without money, or anything else out of Valve. Going back INTO Valve, however is well written, well discussed, community led issue resolution and well hashed bug reports.
With Elite: Dangerous for Linux, Frontier could profit from this support model the same way.
I have never said FD isn't good cross platform citizen. In fact I have always known it's opposite 