What is the future of amp technolgy?

As digital technology makes strides toward the future, amp technology seems to returning to its roots of pre-1960. Tube amps are experiencing a large increase in popularity, and SS amps are generally moving to a more "tube like" sound. Then there is this new digital amp technology, that I don't know much about. Are tube amps the wave of the future, or a dinosaur from the past? Will SS amps finally reach a point when there is no reason to buy a tube amp? Will Digital amps eclipse both tube and SS amps, and become the best of all worlds? Your thoughts?
Question: What determines a digital amp to be a "digital" amp? Are Tact and the amps used in Meridian DSP speakers considered "digital"? I think these amps merely have signal processors built into them?

With the half of the majority playing mp3 off discmans, portable mp3 players and computer speakers, and the other half of the majority wasting their money on home theaters, there really isn't any opportunity for growth in regards to tube technology.

Plus, eventually, even die-hard tube lovers will convert to ss or digital once NOS vintage tubes run out.

Quality of sounds probably isn't the main issue here.
Viggen, that brings up a good question. What is this digital amp technology? I confess that I know next to nothing about it. Maybe someone can enlighten us.
To Twl:

Like so many buzzwords "digital amp" has several meanings:

1) A "switching" (aka Class D, Class H) amplifier in which the output stage at any moment is either fully conducting or fully off. This is unlike a conventional analog amplifier in which the output stage at any moment passes current proportional to the instantaneous value of the input signal.

A switching amplifier produces music by varying the the ratio of on time to off time of the output stage in proportion to the music signal (i.e., by varying pulse width). Typically these amplifiers use some kind of filter on the outputs to reduce ultrasonic noise caused by the rapid switching.

Digital signals (both PCM and DSD) easily convert directly into the pulse width modulation signal required by such an output stage.

2) An amplifier that uses physical modeling implemented in software to reproduce the sonic characteristics of another amplifier (none for hifi use yet) or perform room/speaker corrections.

3) An amplifier that uses both of the above techniques.
Thanks, Ghostrider45. At least that gives me some basics to work with. Much appreciated.
Something's going on when a first-generation product like the Bel Canto digital amps have a bunch of tube-o-philes singing their praises. One can only guess at how good the second- and third-generation amps will be...

Also, and I should say that I do like tubes and what they can bring to a system, as the new formats improve on both the hardware and software fronts a lot of(but certainly not all) audiophiles currently using tubes to smooth out the phase distortion created by their redbook CD players may start to re-evaluate the need to soften edges and fill out the midrange. I think the new formats will likewise soon send a lot of turntables packing as well(again, not all, but most).

My bet is that in a few years we're going to have some relatively inexpensive digital amps and players that will sound so incredibly good that they will relegate the tube vs. solid state debate to a distant back burner. But then again I've lost bets before.