The player of my party's cleric just quit the game (not happy with the combat length in 4e among other complaints). Assuming we continue the campaign (I need to talk with the other players about whether they are happy with the system and campaign), is it possible to continue without any Leader type character? I can give them access to a cache of healing potions, but I'm not sure if that really replaces a cleric. Are there any magic items that essentially substitute for a healing word spell?
I may end up trying to recruit a new player to play a Leader class, but in the meantime, what can I do to make the game still reasonable if we continue without the cleric? I don't want to run a DMPC, so that option is not on the table. I might be willing to use some kind of medic type of NPC companion that can enhance their healing surge value after combats if that would help.
And I bet your combats are long and drawn out.
What happens when you have debuffs stacking on PC's? Immobilised, stunned, dazed?
The player of my party's cleric just quit the game (not happy with the combat length in 4e among other complaints). Assuming we continue the campaign (I need to talk with the other players about whether they are happy with the system and campaign), is it possible to continue without any Leader type character?p.
And I bet your combats are long and drawn out.
So, if you or the players are optimizers, must remain balanced in each role, and value mechanics over story, then it will be a tough slog.
OTOH .... if you eschew optimization, incorporate the lack of a healer as a sort of story line even, create encounters that are slightly tweaked to this party, and adjudicate some DM decisions differently, I see no problem with running leaderless.
See my post above*. You just might find the opposite occurs, especially depending on the DM's monster tactics.
(*Where I generally contend that leaderless combat rounds themselves are quicker than leaderfull combat rounds)

That assertion is so patently absurd that I can only contend that you're trolling. As such, this post will be my last that addresses anything you post in this thread.
A leader not only counters enemy debuffs which otherwise would slow down combats, but they provide their own consistent level of damage, provide buffs to party members to enhance their probability of hitting and damage output, as well as making sure characters don't fall and thus stop contributing to a combat encounter, but they also often offer out of turn attacks and other actions which bypass the regular action economy, thus again speeding up play.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.