HT crazed correct 100%.
All so-called "upgradable" processors are very expensive, they cost arm-and-a-leg to upgrade (recent anounced upgrade for Krell HTS includes analog bypass like in outlaw + new DAC chips and cost ~$2500), it takes forever to upgrade and no guarentee that they will support Firewire soon (if ever).
Cost of new Outlaw processor will be compatible (probably much less) then just cost of upgrade on "modular" processors.
I have nothing against Theta or Meridian - they are increadibly well engeneered and build, but you cannot compare them pricewise with Outlaw.
Buy Outlaw now for $900, and resell it in 3 years (when (and if) new format will pick up steam) for $500. You will have all you need and nothing you do not for 3 years for $400, which probably equal tax on a new Lexicon...