Through the 1990s there were only about 3,000 such denominations.
And even tho there's been thousands of new independent churches crop up, just about ALL of them don't reference themselves as a "denomination."
So, no, there aren't that many...even if there's been an increase in the 2000s.
Beyond that, the overwhelming majority of Protestant denominations don't claim to be THE ONLY TRUE CHURCH body on the face of the earth.
And even the UCG, unlike its predecessor, the Worldwide Church of God -- and unlike the pastor who wrote this piece (Pack & his "Restored Church of God") -- believes the "church" is an "organism" and therefore can't be limited to one organization.
For this one positive aspect of the UCG, just do a search on the link of Pack's piece on the word "organism" and you'll see the UCG quotes on this.
Denomination simply means naming. It is a a euphemism for “sect” or “splinter.” It does not matter whether a group calls it self a denomination or not so long as it is a distinct group not part of another. It IS a denomination, or a sect, or a splinter, or a cult even.