Yes, the bases (and stationary targets on both sides) are absolutely in danger. One thing they do is act as military infrastructure up until the start of the conflict (and in a reduced capacity after).

From what I've read, there are two likely Taiwan scenarios:

1. China targets US bases and ships before sending transport craft across the strait. Sending transports without that first strike would be suicide. Unless this reporting is wildly inaccurate, it is a very clear acknowledgment of the impact of the US military presence abroad.

2. China blockades the island. This opens the door to a Crimea-like soft invasion whose outcome depends on the international response.

In both cases, bases in theatre play a huge role. You talk about "day one" - in either scenario above it's not a one-sided first strike where the plarf wrecks US bases and ships and the pla dances into Taipei. Recall how much advance warning the US publicly gave of the Russian invasion?

When you are deciding on your takeways from the Iran conflict, remember that it's a bombing campaign and not reflective of a full near-peer war.