When a subordinate place is moved from one containing place to another, frequently it changes type in the process, if only changing from "X" to "Former X".
It is relatively simple to imagine an enhancement which would allow such changes to be captured. (I can't speak to the level of difficulty of actual implementation.) The line parsing could be extended to allow for an extra "type" parameter after the date parameters. (An example might be the 1863 move of 55 counties from Virginia to West Virginia, where it is desired to list them in Virginia as "Former Counties".)
There is one further possibility for which this does not allow, which would allow some additional possibilities to be covered. That is the case where in moving from one contained place to the other, the subordinate place changes names. (The example which comes to mind is Elsaß in Germany becoming Alsace in France in 1918.) The obvious implementation would be by adding yet another parameter to the list, but would that over-complicate things?
One thing to note is that if even the first step of enhancement is implemented, it will be used for type changes even where the subordinate place does not move. (For example, Arizona changing from "Territory" as per the "1900 rule" to "State" in 1912.) This is a feature.
--Pkeegstra 14:29, 14 July 2012 (EDT)
Another user has requested on the support page that "alternate names" have slots for "from year" and "to year" just like "also located in". Perhaps both headings could have four fully analogous options "source", "type", "from year", "to year"; that would complete the analogy so that "alternate names" would become a self-referential analogue to "also located here". (That would eliminate the need for my 4th paragraph above.) (In addition, the discussion motivating this paragraph also constituted support for the ability to specify a fifth parameter, variant name, on an "also located in" line.
--Pkeegstra 06:36, 29 November 2012 (EST)