Over the past year, how many new designs have used the 8051 including those used as a core?
Any guesses/estimates?
In what domains would 8051 compete against the ARM Cortex-M3?

First I totally agree with Andys point: "It certainly means that there is really no point in struggling with and 8051-based design when a Cortex would be a breeze (ie, when you're struggling with things like code space, data space, or any other specific limitation due to the 8051 architecture)."

second the viability of the '51 is shown by the fact that Burr-Brown (now TI) chose a '51 when they integrated a uC with their A/D, so did Cygnal (now SILabs), IR chose the '51 core for their motor controllers ....

So, give up wrestling with the'51 but continue using it where it fits.
In my opinion the arrival of the affordable ARMs has made code banking a '51 an archaic approach.

Your question coud be read as "which single processor family should I use" that would often lead to "wrestling the code into the wrong processor"-

Erik

To Andy (aka mr. language expert) is ie, not i.e. correct?