From the list of witnesses, it looks like show trial. Ms. Dittmar's job is to promote Orion/SLS. Gerst's responsibilities are technically as much about ISS as Orion/SLS, but given that he spends most of his time on the latter these days, I don't see him speaking up for ISS. Thus, there will be nobody to speak up for retaining ISS past 2024.
So, I make three predictions:1. NASA will be put on the track of withdrawing from ISS in 2024. The decision will not formally be made during the hearing, but that will be the drift.2. Noises will be made about privatizing ISS or offering NASA's share to the international partners, quite possibly in tandem with the notion that NASA would rent space aboard ISS.3. There will be no serious discussion of the difficulties or costs involved in either disposing of ISS or giving NASA's share to a commercial entity or foreign space agency.
Regardless of whether my hunches are correct, ISS's actual future will remain unclear for years. Recall that under Bush II's Vision for Space Exploration, NASA was to withdraw from ISS in 2015. No funds were ever allocated for de-orbiting ISS, however, nor, to my knowledge, was any serious case made that any entity, commercial or governmental, would be likely to pick up NASA's share of the operation. It was simply assumed that ISS expenses would magically vanish from NASA's budgets. The stage was being set for a funding crises in 2015. I would guess that's a very possible outcome now, with the crisis occurring in 2024.