Since it's now official that the latest "bonus" we've been given is episode #4 of "Mrs. Columbo" (on the heels of episodes #2 and #3 in the last two sets), I think we can now say with certainty that Universal is going to palm off the entire run of this show when all is said and done over the course of future DVD sets, including releases of the ABC shows. It represents a cost-effective way of making money off episodes of a show no one in their right mind would ever buy if it were a stand-alone release, especially given how "Columbo" is the best-selling title among 70s Universal properties.
I won't be a bit surprised if Universal decides to release Season 6 as a stand-alone even with only three normal Columbo episodes and pads it out with the two hour Mrs. Columbo pilot episode.
I know Mrs Columbo is considered blasphemy around these here parts, but I for one would love to see it.
Some of the later series have so few episodes that the only option is either to bundle two together or pad them out with Mrs Columbo episodes.