Each edition of D&D has faced the question. Buff casters, or nerf casters.
When they ask the fans, they rarely get "leave them alone" as a response. People either think they are too good or not good enough. So let's take a look:
AD&D: uncapped damage spells.
2nd Edition: damage spells gain caps (no more than 10d6 fireball or 5 magic missiles).
3rd Edition: several improvements on casters such as not losing AC when casting, more spell slots, a separate pool of cantrips, Concentration as a skill, scaling DC's.
3.5: initially a mild nerf to caster save DC's (the Feats that increased them were lowered from 2 to 1). y the end of the edition, however, spell bloat, feat bloat, and caster PrC's that required them to give up almost nothing for more power made it a spellcaster's paradise.
4e: complete rework of all classes to try and balance their power.
5e: casters were given back a lot of their powerful spells; at will scaling cantrips were retained from 4e. Less spell slots and limits on how many spells could be cast at a time (no bonus action + leveled spell; only one concentration spell) somewhat balance this out; balance somewhere between 2e and 3e initially, but over time, casters get more powerful options.
If this is a trend, then it would follow that the next iteration of the game will feature nerfs to spellcasting, no doubt followed by an edition that "makes casters good again".