Yes, standalone was and is really a problem! That's the reason I planned my setup with different synths syntheses:
The main problem is, that many manufacturers always built complete new machines with new sound engine and new here and there ... and don't integrate the good old things there., too.
As I was young I played with grooveboxes, too (MC 303, 505 ...) and the MC 909 for example was a good concept but Roland never finished that concept. The MC 909 still has some bad bugs so you can use it but you can't use it only standalone if you wan't to produce a high quality track ... ok some freaks perhaps can do this ?
OK, with Elektron it's a little bit similar. I think, the Monomachine would need some more other filter types and some more new machines, too ... then perhaps I wouldn't need 4 other synths, too? - but who knows what comes up in the future from them? What I like from Elektron is, that they improve their old machines continously. That's a good strategy and perhaps some day you can upgrade Monomachine / Machinedrum with an USB Port?
And yes, USB Audio and Midi will become standard but many of that modern synths sound like plugins but are more expensive!
For example the Virus TI2:
It's has a big and modern technic but its sound hmmm ... I think you can replace it with Omnisphere, Trilian, Sylenth and Vanguard together and save a lot of money. This plugins you can buy for 750 EUR together and can use them easily with many instances in your daw without hardware mixer ... so what is the need for a Virus TI2 if you still have a good PC, with DAW and great plugins and want to work with your pc? For live ... ok but for DAW?
Or look at the Korg Kronos:
It has many syntheses and a great sound .... BUT the sequencer is terrible - so only for that you need to use a brakelight Kronos Plugin, too ... so you pay 3000 EUR for a all-around entertainer keyboard with fantastic sound but nothing more! Please, don't show this post the Korg Forums - as I posted my opinion about the Kronos there, they hated me!
If they will create hardware in the future which can do special and freaky things, like the Elektron sequencers for example, which you can't do with your DAW or plugins, then PCs will become old!
Especially freaky and integrated sequencers in a hardware product are the goal for me!
And I found this, too:
http://www.synthtopia.com/content/2011/07/15/kenton-intros-usb-to-midi-interface-eliminates-need-for-computer/And yes you are right! For edit-, cut-, samples work I prefer my PC, too and will still use it for that and fast remixes ...