EIP-4844 Question

Hey I just read the EIP proposal and have 2 questions https://eips.ethereum.org/EIPS/eip-4844

1. It says the data blobs can be discarded after a while. What is "a while" in practice?

2. As rollups work right now if someone nukes all rollup full nodes I will at any time be able to reconstruct the state just from L1. But after EIP-4844 rollups have an additional trust assumption that at least one rollup full node exists that is willing to give me the data. If data is unavailable users funds are frozen forever. Is that correct?

edit: formating to be clearer