I think GV is remissed if they aren't looking and considering changes while things are changing around them. I believe GV won their league this year with a record of 6-4. If I recall correctly that league is split into north and south divisions, the South Division is traditionally VERY weak.
This is not a knock on your school Grevw Fan, I feel that GV is usually fielding nice teams and usually a South Division winner in various sports if I recall correctly. My thought is that if the people in your district are just ok with winning a title in a crummy league then you're right they will/should stay but if you are looking to accomplish things at a state caliber level it is not likely the OHC will prepare the team.
Also, as it pertains to next year's team, from what I have read and seen that could be a great team but these type of league changes typically don't happen the very next year. From what I have observed, it's usually a year or two transition into a new league so next year's team should have no problem sweeping the OHC. I'll be excited to follow their record next year...