They already buffed them twice, it will be ridiculous to make them anymore powerful. Machineguns aren't meant to be a main weapon of any kind.
SLs, SPLs, MGs, Flamers are all underpowered.
MLs are the correct backup weapons of choice for most mechs.
MGs could stand to be buffed to... 1.5 DPS. Which when you take into account how much it sprays everywhere, isn't that much damage.
In a light mech, attacking another light mech, you'd have to be a supremely talented player to keep your DPS on target the entire time, much more so to keep it on target on a specific spot.
Also, 2MGs to 1SPL is an erroneous comparison - 2SPL to 2MGs is a better comparison, given the ton of ammo you need to carry.
DPS is definetly worth less than upfront damage in this game - having to keep your mech pointed at the enemy mech is a big liability that is wholly underrepresented in the balancing stakes of this game.
At 1.5 DPS (maybe even 2), MGs go from jokey sub par weapons to interesting weapons that could actually be worth while despite their drawbacks. Of course at that DPS, you'd want to take out the 'crit seeking' capabilities of it... not that that ever did much.
At the same time, SLs and SPLs could stand to be buffed. 90m to 150m would be ideal. Maybe a lower recycle time on the weapon as well.
And flamers can definetly stand to see a big damage buff - again to account for the fact that it's a constant DPS weapon where your mech needs to face towards the enemy to deal damage.