Season 10 promises to take Clark's superhero identity out of the shadows, while Clark wearing glasses becomes the norm.
In the Season 9 Finale, Clark had a premonition of his own future as Superman. Doctor Fate saw Clarks future in a vision in "Absolute Justice". And in Legion, Clark learned something of his destiny. Clark awoke, to find a box near him, with a note from Martha Kent, and his Superman costume, that he'll wear in the future.
All principle characters, the ones that you see in the credits, know Clark is The Blur.
Perry White may appear in a few episodes, and Chloe Sullivan will appear a lot less.
The Season 10 Villain is Darkseid
Green Arrow was abducted and captured by Darkseid's parademons, while Tess Mercer's body was retrieved by Granny Goodness. A loyal minion of Darkseid.
Sending Tess on the wrong side of the coming Apokolips, as the Red Queen (Martha Kent) predicted. Darkseid will use his Omega Beams to resurrect Tess Mercer, and a 'mother box' device may be used to reprogram her into being a loyal servant of Darkseid. If the show decides to go this route, even if it is only for 1 or 2 episodes.
Season 10 may introduce Darkseid's love interest, a young woman named Diana, a mysterious princess from Paradise Island. In the future she will be called Wonder Woman, however, she is a few years behind Clark, in establishing her superhero identity. This part about Diana is pure guess work, but I'm positive that she will appear. She could be another member of the Justice League, although, not initially, as they would want to introduce her character properly first. As an individual, then make her part of the team.
If this sounds to far fetched to be true, then remember the Wonder Twins, that seemed far fetched a year ago, yet, they have appeared on Smallville.