Ask HN: Would you be interested in becoming an engineering mercenary?

Looking for a feedback on a startup idea, fuelled by the recent boom in engineering jobs market.

Let's say you join a well-funded Silicon Valley company on a full-time basis (and a Bay Area level of salary), but for a limited time: usually between 6 and 12 months.

You get 1-month notice before the engagement ends and after that receive fixed monthly retainer until you get another similar offer.

What would look like a reasonable retainer to make this worth considering for you?