The roles each new champion can viably be played since 2014.

Pre-dominantly played:

• Support
• Mid

Pre-dominantly played:

• Support

Pre-dominantly played:

• Top

Pre-dominantly played:

• Mid

Pre-dominantly played:

• ADC

Pre-dominantly played:

• Jungle

Pre-dominantly played:

• Support

Pre-dominantly played:

• Jungle
• Mid
• Top

Pre-dominantly played:

• Top
• Jungle
• Support

Pre-dominantly played:

• Jungle

Pre-dominantly played:

• Top

Pre-dominantly played:

• ADC
• Mid

Pre-dominantly played:

• Mid
• Jungle

Pre-dominantly played:

• Mid
• Support

Pre-dominantly played:

• Top
• Jungle ???

---

Final tally:

TOP LANE:

JUNGLE:

MID:

ADC: (Kindred as an off-build, much less effective due to nerfs forcing her to jungle due to increased reliance on marks.)

SUPPORT:

FROM THIS, we can conclude that the most likely new champion is an ADC if Riot wants to provide every lane something new to learn and play every now and again: only two champions were expressly designed for the ADC role. That means that unlike other laners, ADCs only really had two or three new champions to learn at best. Interesting to note that none of the fourthree marksmen are 'standard' marksmen. Kalista is heavily reliant on her Support and her kit has a bunch of utility as well as hops. Jhin's kit has a lot of utility and zone control, and he doesn't gain ASPD from items. Kindred has a utility ult and relies on marks for her Passive damage, and is also designed to work in the jungle more than a lane.

(Do feel free to correct me if any of these roles are played more frequently in other lanes, though! Just listing the most viable options that are worth picking up as someone in those lanes, instead of some niche off-pick that isn't reliable.)