First off, this is NOT a post about creating an 8th school at all. Instead, I want to discuss view points on the topic of if an 8th Main School came to the game. Please note, there are no confirmations on an 8th School coming at this time.
Often when I hear players coming up with new main school ideas, they will face backlash and get shot down by players. There are concerns to making a new school. What will it new? What about all the gear for it? How will it look? Who's the teacher? Where's a classroom? So on and so forth. Sometimes, players just say things like it would be too much work for KI to make an 8th School and wouldn't be worth the time or effort. I would beg to differ.
Ultimately, it's KI's chose if they wish to do the work to make an 8th school. If they have the budget and are willing to do the work, let it be. Creating an 8th school is a whole update in it's self and we've seen KI make updates for Wizard101 that are just updates adding features (Advanced Pets, Gardening). And if you notice with other MMORPG's, they do bring out new classes every once in awhile, and KI does do this with Wizard101, but they only create Supplementary Schools.
When players talk about things like gear and all that, KI doesn't need to make many new gear models. If you notice, every world reuses gear models for the 7 schools and KI makes no more than 4-5 gear models per world now so just coming up with a design would be the only thing. Wands would be the only concern, but even then that's nothing to frown upon. Mastery Amulets, and Crowns Gear is also nothing to cry over.
The only real concern over an 8th School, besides PvP's rutine inspection and cries of OP over new schools, would be what it does and how players will adjust to it. Currently, there isn't a need or immediate desire for an 8th School. I am very open an 8th School coming to the game, but it has to have a unique purpose. As it stands now anything that could be done for it, could be taken up for another school. Like I've always wanted a spell that can take my useless blades and shields away and give me something more favorable like a bigger universal Blade or Shield or even health, so Life, Ice, Balance or even Shadow Magic could do that. Honestly, I would leave it up to the developers to create a purpose for an 8th School.
I could picture schools like a Water school with a Tear Drop sign, or a Mechanic/Robotic themed school with a Gear or Wrench sign, or a Time school with a Clock sign, or even an Alchemy school with a Potion sign and such, but they all have to have some kind of purpose that can't be taken up by Balance or Storm or something. Currently, there is no solo school about doing only AoEs or about tearing things about and creating chaos; not pulling from anything (opposite of Balance).
In conclusion, I think it's fine if KI were to make an 8th main school, as long as it's purpose is really good, won't look like a complete copy from another school.