Bungie announced a slew of changes to weapon archetypes in Destiny 2 which will help out some less powerful types in PvE.
Hand cannons, scout rifles and machine guns have been affected by precision damage nerfs in Shadowkeep that brought them to near or total uselessness in PvE. Hand cannons can still find some decent use but with scouts and MGs, you are shooting yourself in the foot due to other options being much more potent.
Without providing an exact release date, Bungie stated that the near future holds several buffs for these weapons. Scout rifles and hand cannons are popular among the players and they've been asking for buffs for quite a while now. According to the latest TWAB , these buffs might have something to do with getting these two weapon types to be more effective at clearing minor enemies in high-end content which probably translates to reducing the effects of the aforementioned precision hit nerfs.
Furthermore, Bungie announced they will be looking to give the players more reason to use Exotic primary weapons in high-end PvE and combined with the buffs aimed at hand cannons, one has to get a little bit excited about the implications for Ace of Spades and Sunshot.
As for the machine guns in PvE, Bungie's testing showed that these weapons are just not doing their job, which is something the community has been pointing out for almost two years now. Anyway, the buffs for these heavy weapons are coming in Season 15 and if the TWAB is to be trusted, the changes will be noticeable.