Probably a bit of both.  While there's always that chance of a conventional conflict, the "savage wars of peace" seem much more likely and more likely venues for the application of military force.

The newly minted enthusiasm for Special Forces (SF) type "advisor" missions, rather than Special Operations Force (SOF) direct action, is probably budget driven.  But, reviewing history within the conventional military, you will find pretty deep running antithapy against a true SF mission.  An example, the old SF was the strike force of the CIA in the late 50s early 60s and though the teams were military, the CIA station chief was usually calling the shots...in Laos, the Congo, in South America, etc.  In about 1962-3 the brass rebelled at having one of its military units commanded by the CIA and withdrew the secunding. 

 

It seems that whenever a "special" unit dedicated to the original SF function is created, as soon as the creator is gone, it is subverted by the straight legs into something they can understand.  Abrams hated the SF when he took over in Vietnam because he saw them as a loose cannon, not subject to traditional military discipline.   He tried his best to return it to being just another army unit, sacrificing Col. Rheault, trying to put a straight-leg crony in command (he broke his leg trying to get jump qualified in one day), etc.  After Vietnam, the conventional brass were more or less sucessful in controling SF which was allowed to deteriorate.     

 

But what is that origianl SF mission?  What is an SF "advisor" as opposed to a Military Assistance Command unit?  The original SF was a complex professional military role that worked with locall groups of indigenous peoples to create a para-miltary force.  The SF team did it all...recruit, train, lead and tend to the social needs of that para-miltary force..."win hearts and minds" if you will.  Typical of third world, such a local based militia unit is highly loyal to the individuals who created and recruited it because such warfare in the villages is essentually tribal..very personal.   Thus the SF role is far more complex than what MACV did...which was simply to work with and train the established military.  

 

The skill set for this SF force creation often requires some mavarick thinking and an almost mecernary professional soldier attitude...ability to get along, understand, set examples, lead, be comfortable, with indigs.  Then a thorough knowledge of the 5 skills needed for a military unit...Intelligence, Operations, Communications, Weapons-engineering, Medicine.

 

One other thing is needed.  That is "team integration."  There is a reason the old SF (as opposed to SOF) unit was called a "team."  Everyone on it was presumably a professional with special expertise in one to three areas and they were trained to treat each other in that way.  For example, a team leader would not usually question the commo sarg when he re-wrote to message reducing it from 350 words to 40.  This is a concept that is usually a little alien to military command structures.

 

But whatseems to be happening today is that the SOF command has become an elightened career path.  As long as SOF was a knife-in-the-teeth direct action commando group, it fit into understandable military structure.  As soon as the weaknesss of that structure to handle indigenous situations such as Afghanistan and post-invasion Iraq became obvious, apparently some momentum begun to restore the SOF branch to its roots...to the much more CIA-old SF ideal.  Now that unconventional path is becoming ascendent (CJCOS is SF), and money is being allocated and many good men secunded from all branches.  So...it is entirely predictable that the regular forces will try to get in on the game, regain control...and the cycle will start all over again.  Do you remember the 1950s when all three services were competing to develop rocketry?

 

When SOF special operations force direct action, Delta-force type, was the rage, we ultimately ended up with 5 or 6 separate commando units, even the Air Force had one for god's sake, not to mention Navy Seals.  As a result, the unity of the mission was somewhat splintered fractured.  I hope unity of the new/old SF is able to be maintained...and to be honest, perhaps consideration should be given to have it commanded operationally by the CIA rather than conventional military.   

The Army declares it wants an "expeditionary" mission, and considers an "advisor force", the USMC is going the "advisor"-"small wars"-Light Infantry way with training that a few years back would be strictly SOF territory.

Is this a sign of the times, a "fashion" so to speak because of current conflicts, or the way of the future?

Any opinions?

Before it was SOF territory it was USMC territory. Remember the "Small Wars Manual". The Air Force, Navy And Marines are all doing training where they see a need and there are no SOF. Problem with SOF is manpower, too many jobs for them to do.
Problem with the Army doing an "expeditionary mission" is that the Marines bring there guns, armour and air support with them. The Army can move Light Infantry quickly but there guns and armour take 2 to 4 weeks (or more) to get there leaving the Light Infantry hopeing no one attacks them with tanks. Then they have to ask the Air Force for support.

The C17 was suppose to take care of moving guns and armour quickly but with so few made (Air Force has to have those fighters) they can not be used in that role.
You may have noted that before the Iraq war we had lots of troops in place quickly without there heavey equipment. If there had been fighting well trained troops on the other side they could have really hurt us. About the only troops with heavey equipment were the USMC.