Hmm, well I do enjoy a good WW2 a/c debate, and respectfully disagree re: the MiG-3.
There were @ 12,000 fighters in the VVS at the time of the invasion, @ 6000 of those were I-16s. There were 1200 MiG-3s in service, with another 1900 built by the end of 1941 beg of 42. 3260 total, using your data.
The I-16 didnt need replacements to stay numerically top dog, as the MiG-3s were also being lost in the fighting. By no means was it just the more obsolote types being lost, and the MiG-3 shared that burden.
That and I have seen several quotes indicating that more than 1/2 the I-16s produced were still in service by 1943. I just dont see the MiG-3 ever being the most numerical VVS fighter, it was dwarfed by the I-16s #s in 1941, and after that year, it stopped production, to be outproduced by the LaGG and Yaks. The "sweet spot" for the MiG-3 would have been right at the end of 1941, where it was probably the second most numerical type, for a few months.
Also, it has to be said that there were many I-16s that were not stationed in the West, facing the invasion, but in the East, facing the Japanese, and in other quiet sectors where many of them would have escaped the cauldron of the fighting, thereby giving it a bit of a cushion #s wise. I-16s were transferred to the Soviet Naval Air Forces as newer types were brought on line in VVS units, rather than be just retired.
"Soviet Aces of WW2" by H. Morgan is a good source.