Lines of credit against assets are typically interest only, interest rate pegged to however many basis points above the current fed fund rate.

There is no balloon payment ever due if you simply pay off the interest indefinitely.

Of course there is always the possibility of a margin call against the loan where if you lose X% of value on the securing asset you may be liquidated of it and the proceeds used to pay off said line of credit.

There are a million caveats and different loan structures so I’m sure some finance bro will be along to correct me shortly. But overall for normalish folks this is more or less the correct mental model.