I can only speak for the teams I'm familiar with in the upstate. Christ Church has a few solid players remaining on their roster, but Seiler was their real elite talent. Southside Christian is in the same boat with a few talented guys (Braden Myus comes to mind).
St. Joe's is where the 1A upstate talent is at right now. They beat JL Mann and Eastside last year and never gained much attention because they are 1A. Coming into this year they have 4 guys who played on the CESA U16 boys team that played for Tormey in the nat'l championship over the summer (Brennan Koslow, Chris Heijjer, Ryan Bertling, Josh Bertelsman) - all of those guys could play at the next level. Senior Austin Burnikel has signed at Clemson, following in his brother's footsteps. They will graduate a lot this year, but have young talent to fall back on (Jose Cera, Reilly Koslow (GK)). They also lost Michele Bottari who is with the DA..
In my opinion, this team could play with anyone in the state when healthy. The real challenge will be a few years down the road - not sure anyone can own 1A like Christ Church did for so many years.