I am updating a 100amp service in an old house. The meter is located on the pole. The house currently has a non weather proof main panel on the exterior of the house and another remote panel in the middle of the basement. The exterior panel is very unsafe and badly corroded.

I intend to mount a 100amp exterior weather proof disconnect on the outside where the main panel is now and a new 100amp main panel in the basement where the remote panel is now.

The main panel will be about 20 feet from the service entrance. My interpretation of the NEC would be that I should run the ground rod connections to the exterior disconnect and bond the neutral to ground in that box. I should then run 4-wire to the main panel and keep the neutral isolated in the main panel.

Any opinions ?

That's right, they are separate from there on. You don't want your ground carrying current.