As for digital connections.
Once again no point in waiting. There is no uncertainty, Not because we have something that works, but because chances are we never will. Unless the SONY SuperMAC interface (48ch (dsd or pcm), proper clock and control over cat5 good 300m)which is now being ratified as an AES standard, makes it to home audio.
1394 is a software mess, everyone is doing their own thing. To fix compatibility mfg's would have to invest heavily into software.
1394 also has some clock issues that some designers can deal with most can't.
HDMI is a joke it's only good for video since it doesn't even cary DSD.
So if you are awaiting for that "player" that will connect to your pre pro with a single link, well you can get them now, from Denon, Meridian and alike.
Other then that, don't hold your breath.
There is not much wrong with short set of nice analog cables going into a pre pro with proper analog bypass. Unless you hate the idea of paying for a nice set of dacs twice. However this allows for tailoring. You can keep your fancy da you got for your cd's and not have to worry about if your new player will paly cd's ok or not (Most will.).
So you may be thinking Denon 5910 for all it's linkage (1394, denon link, HDMI) but realistically unless you get a denon box, these will only be good for video (HDMI).
... age uncertainty... Everything digital is basically end of life by the time the product hits the market. Compatibility going forward will be meaningless. So there is really nothing you can take for granted. Everything is a giant uncertainty. And even when you think things are in concrete, someone else will come along with something faster better cheaper.
Some mfg's are already talking 384khz and Wide DSD (8bit).
I for one use all these connections and technologies very happily in a very nice and simple system.
I use HDMI for my cable box to the projector, I use analog from my UNI Player to my Classe SSP75, I use AES from my HTPC to the classe and DVI for Video from the HTPC to the projector. The classe is superb decoder and DA for all PCM low ress. The Marantz plays DVD an SACD over analog.
So you can have it all today enjoy it for what it is and stop worrying about obsolescence, because they are all already there.