Just out of curiosity... Which of both "weapon classes" could you see become rather obsolete in future? LMGs or DMRs within the squad? 

neither?

I would say it depends on whose squad you are talking about.

For example, the future USMC squad has a DMR, but no LMG.

Whereas the future US Army squad has 2 LMGs, but no DMR.

I thought the army bought the M110 A1 as  SDMR? 

Yeah I mean generally or globally 

The M110A1 is 7.62x51 caliber.  It seems rather unlikely that a 7.62 DMR would be used in a future squad equipped with 6.8 rifles and machine guns.

Generally or globally, I'd still say it depends upon whose squad.

The Russians currently have a LMG in the squad, but no DMR.

Other countries have both types, and may or may not change.

But IMO the squad DMR is more likely to go away than the LMG.

Like Stan, I would say it depends on the organization. Give everyone a magnifying optic, do you really need an official DMR? If it's important enough, just give a target a nice burst from the LMG. Issue a heavier barreled assault rifle, teach your troops how to use full-auto properly, do you really need an LMG? 

Then again, the Marines are merely putting their LMGs into storage. The M249s will be available if the situation requires them.

According to Battle Order, only six M249s are being kept in the company. 

That means not all of the squads in each platoon could be issued a M249.

In my opinion a DMR is unnecessary at the squad level with the standard issue of magnified optics.  An argument could be made for them at platoon though.

My philosophy is that the squads weapons and associated calibers should be optimized to about 300m and effective on point targets out to about 500m.  At that point we're reaching the limits of what we can expect an average rifleman to reliably accomplish even with optimized weapons, calibers and optics.  I would expect the weapons squad (or heavier weapons attached to a patrol) to be using their supporting arms against threats near and beyond this range to allow the maneuver elements freedom of movement.  Alternatively the squad could have munitions capable of reaching out beyond this range if weapons teams are not in a position to provide support, such as AT4 like weapons, Pike, or suicide drones.

During the final assault or close defense (say under 100m where supporting arms are having to lift to avoid fratricide), I want clear superiority of effective fire from the squad against any peer threat.  That means low recoil and significant volume and duration of fire.  This can be achieved through a variety of means -- either every rifle can be select fire, or there can be dedicated automatic weapons that reload quickly to minimize down time (ideally drum fed), or a lightweight belt fed automatic weapon that can fire for longer before having to reload. All of these approaches have their advantages and disadvantages, and while I personally prefer the last approach, I recognize that over the span of decades trends and preferences come and go. Therefore, I believe the fireteam composition should be designed to accommodate any of these approaches so it's a durable organization in the face of changes.

As such, I think a good composition for a fireteam is six: Three riflemen (one being the fireteam leader), two automatic riflemen (with either a drum fed or belt fed automatic weapon), and one grenadier (with a multi shot grenade launcher firing medium velocity grenades).  The squad would have the SL and SSO, and 2-3 fireteams depending on type (mechanized, light etc)

Why two automatic riflemen in each fireteam? Because if the fashion of the week is drum (well, let's be honest, magazine) fed automatic rifles, then while they can reload faster, they also have to reload more often.  Having two helps offset this.  If the fashion returns once again to belt feds, and we start seeing two Mk46 or KAC LAMG in the fireteams? Well, sucks to be downrange of that capability.

Any more opinions? Iam quite curious lol