Two sides to this: Yes, Fleck is the ultimate face of the program. But, having good assistant coaches is important -especially for a coach like Fleck who is not a real hands-on, X's and O's guy. Also, assistant coaches do a lot of the field work and groundwork in recruiting, so at the very least, hiring new coaches means they have to get up to speed on their recruiting territory.
In other words, it's not the end of the world, but it is a concern. As noted, people use all types of stuff for negative recruiting. Too much turnover on a staff in a short period of time doesn't look good, and it can be spun as a negative.
In the end, it all comes down to wins and losses - if the Gophs win 7 or 8 games next year and go to a bowl game, everything is fine. But, if the Gophs have another 5-win season and don't go to a bowl game, that is a different kettle of fish - maybe even lutefisk. (ask a norwegian)