No. Corporations and small businesses still need to keep track of profit/losses. States still may have state income taxes.
"States still may have state income taxes."
Few, if any, states will retain their income taxes. There are a number of reasons, not the least of which is that every state income tax in existence today uses the federal system as its foundation. Without a federal income tax, any state would have to build its own income tax system from the ground up if it wanted to continue to tax income. That would politically and practically a very difficult undertaking.
You are correct - large businesses still need the accountants, but sole proprietorships and most small businesses wouldn't...and since I live in a state without state income tax I didn't factor that in for you less fortunate -- of course y'all could move here and help push up my real estate values !!