I say it will be quicker for Amtrak and Brightline to move forward than anything locally for a few major reasons IMO.
1. They've both done it before. They know what they are doing. No entity in Jax can say that...including JTA.
2. They already operate an intercity rail service. No entity in Jax can claim this. So much of what we'll struggle for years to figure out has already been resolved by these systems.
3. No matter what anyone thinks about Amtrak, this intercity rail service is already in operation in Jax. So with them, we're not talking about building something new from scratch. Instead, the conversation should be around adding an extra stop(s), similar to Stuart, Aventura or Cocoa getting an extra stop on an existing Brightline service that already operates through their communities. Adding a station downtown will always be easier and cheaper than JTA establishing a new rail service on tracks they don't own.
4. Brightline already has the rights to operate their service on the FEC. With them, it's not a matter of if. It's a matter of when, ridership feasibility and cost. A vibrant downtown Jax can make this happen sooner rather than later. So the local challenge is making downtown vibrant. Not figuring out how a transit agency that can barely run a reliable bus service can expand to running a passenger rail operation.