While I do agree that it's likely Epson has something bigger and better in store (possibly just around the corner), I don't think that means the 3800 will be short-lived. My guess is that when/if Epson comes out with a new inkset and corresponding printers, they will be targeted squarely at the pro market and priced accordingly; ie the 17" model will be priced more along the lines of the Canon/HP models, not the 3800. My guess is whatever new technology they come out with won't "trickle down" to the price level of the 3800 until they either feel they can do so without hurting sales of the pro models or feel they have to respond to something from the competition.
I agree. The 4000/4800 change was largely (totally?) an inkset change---the 8 ink printer remained an 8 ink printer.
The 3800 is different, creating a new class of printer; low end pro, 9 inks with an 8 ink head, sharing inks with the 2400 (and likely with its replacement). In fact, it seems like the 3800 could marginalize or even kill the 4800. I simply don't believe that is Epson's plan.
At the high end, the replacements for the 4800 and up will get a new inkset (no more black switching, add some colors, maybe glop, etc.), new heads, and will aim to exceed the new high-end HPs. This differentiates the 3800 and the 4800 replacement, making the 4800 replacement relevant and competitive again.
I expect that the short-lived printers today are the 4800 and up, not the 3800.