Well there is a difference between two sorcerers and two wizards vs a 'all spellcaster' party - druid, cleric, wizard and sorcerer are all primary casters. Add to the group bards and warlocks and you can easily setup a group of 4 primarily casters in 5e that will work. At the same time you could go without primary casters and it still is viable in 5e. Since you don't need designated healers or mages I would feal very confortable going with a ranger / paladin / druid / bard without min-maxing and playing with multiclasses for example with no worries because 5e isn't based as heavily on buffing and de-buffing as older editions. The system also doesn't truely support traditional MMRPG roles with tanks/healers/dps - you can't force enemies to attack tanks, healers don't heal efficiently, but there are control and dps builds to be fair.
Don't get me wrong you can create parties that will have a harder time, but its still far more forgiving than other systems.
