Everybody's game is going to be different, of course. An all-Wizard game is going to differ from a game following a mix of mortals and supernatural folks.
One strategy to make sure everyone is contributing is to note everyone's top skills, and then make sure those are being challenged. Another way to ensure screen time for all is to regularly compel each player's concepts and aspects, rather than making each session a monster-hunting episode. Also, remember that characters can be helping with Maneuvers in any combat, making it easier for the main combatants (wizard and some other type of fighter) to end conflicts more decisively.
As has been proposed in other threads, human cannon fodder supplementing a given supernatural threat should discourage the Wizard from deploying some of the more destructive battlefield magics, for fear of a First Law violation, allowing the other characters to play a more active role in combat.
However, if violating the Laws of Magic is not a restricting factor in the game - due to either a non-mortal spellcaster, Sponsored Magic, or failure to enforce Lawbreaker and other setting consequences for killing humans - then yes, the spellcaster is going to end up being more powerful when freed of the consequences Harry had to grapple with every time things got hot in Chicago.
But obsolete? No. Spellcasters cannot have all of the skills and still be good at anything, so other characters are needed to help move things along with their own specialities and aptitudes. And if those characters' aptitudes aren't being brought into play or their Aspects challenged, then it make sense that they seem obsolete - because somehow the table has allowed them to become obsolete.