Sunset
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The strategy in general is to never pay off the debt - as long as the underlying assets grow faster than the debt your net worth continues to grow. I found some articles referring to this as strategy "Buy, borrow, die". The estate gets the stepped up basis so when they liquidate assets to pay the debt to settle the estate there is basically no capital gains tax. I don't think you need cooperating heirs - the executor should have the power to sell assets to settle the estates debt. It is possible tax laws change in the future so there is that risk.
I don't think estates get a stepped up basis as the estate is the same as the dead person. It's the heirs that inherit that get the stepped up basis.
If I'm wrong about this then what you are saying makes great sense.