What was claimed
The Verge titled an episode of its Decoder podcast "SpaceX's ambitious, expensive gamble to replace AT&T, T-Mobile, and Verizon". The host says it is now clear that SpaceX is serious about competing with the three carriers.
What is actually there
The facts in the description are these. Last week SpaceX agreed to buy a large block of low-band spectrum. The FCC approved the deployment of 15,000 next-generation Starlink satellites. And last year SpaceX agreed to buy close to $20 billion of EchoStar spectrum. All of that is licences and permissions. The description mentions no subscriber numbers, no launch date for a carrier service and no price plans.
The host himself adds a warning. He has covered telecom for a long time and says companies often announce what they want to do until they meet how expensive it really is. In his words, the telecom graveyard of pivots, bad ideas and failed acquisitions is vast. The episode asks whether SpaceX can pull this off, which is a question, not an answer.
Why the headline is too strong
"Replace" implies customers leaving their carriers. Nothing in the material shows that happening or even scheduled. A better reading is that SpaceX is assembling the ingredients to enter the mobile business, with the hard and costly part still ahead.