I sense a misunderstanding here.

The formula cannot be retired, since it is a financial truism/unity - there always is one and only one best-fitting trendline for USD/BTC all time dataset. It's like your shoe size is a certain measure and you cannot retire it.

Disregarding the use of the trendline at the point that has historically offered the least risk and best upside, is not smart in my investment philosophy. Quite the contrary, you should now make the adjustment to benefit most from the fact that we are at such a cheap and low-risk point.