Do yourself a favor and get a switch with SDI inputs. Then get a set of these to cover you until you retire your SD/Composite sources. That way you can still use one deck to control all inputs. You could then go with something like the ATME 2 M/E to handle it.
If you are sure you need 30 HD inputs, you're going to be looking something like a Grass Valley Karrera.
If converting your analog signals to SDI isn't the way you want to go, you can get a custom HD/SD from Ross like their Acuity line of switchers.
More flexibility; more money.
I helped a client put the upconverter/ATEM solution into play, but I'm not a huge fan of ATEMs as they have limitations I hate to work inside of. However, the solution worked fine for the client I did the work for.