I don't know if this specifically has to do with 'saving F1,' but on the subject of track characteristics I think elevation and camber change are very important ingredients for a great track. Also I think fast chicanes (think Nurburgring and Imola chicanes at Magny Cours, the Masta Kink at Spa, or the [first] swimming pool chicane in Monaco) are quite entertaining, certainly vastly moreso than slow chicanes. The track needs to undulate way, way more than currently allowed.
It's also important that mistakes are punished. There needs to be the real possibility of (big) crashes. Get rid of the mind-bogglingly easy runoff areas like at Turn 3 in Catalunya.
Lastly Tilke gets an unfairly bad rap. He is working within extremely limiting regulations.