It's only logical that riot tries to create skins for the more popular champions. Why would you release something that isn't going sell. That's the reason why we see so many Lux, Ahri, Vayne, Yasuo & Lee Sin skins. They are just played extreemly much and even when they are not meta they are still played whenever they are open.
Than their are picks that have an extreemly high winrate in any meta while still are very decent to play like Warwick, Evelynn, Elise and Lulu. Picks like Janna are theoreticly on the list but the funrate while playing her by the average person can be questioned.
Than you have the meta picks that vary depending on the patch. Useally you will notice skin releases when that certain pick was meta for a while. The perfect example would be
that litterly had a skin release one patch she was nerfed after been in the meta for almost a year. While before that it was been years before she had recieved something.
Let's just guess what champions will have a hugh chance on getting a skin next year:
- Malzahar (been meta in mid for almost haf year, and probally will continue with the item buffs)
- Katarina (has consistently been replacing Ahri in the god tier list)
- Evelynn (offcourse she is, new model so new skins)
- Nasus (the dog has been meta for haf of a year)
- Gangplank (to much abuse)
- Kog'Maw (what do you expect)
- Teemo (god no)
- Lulu (unballanced for more than a year now, it's going to get another skin)
- Zoe (jup...)
##Maybe
- Ezreal (adc, jungle, adc again, still situational but the pickrate is still ok, I give a 50% chance on this one)
- Twitch (maybe)
- Janna (still the queen, same chance as ezreal)
- Taric (meta for about a year now)