I did not suggest that we call blueprint itself a retronym. when I said this is *related to the retronym, I meant *related. I no longer like using the word opposite since (as we've seen in the past) opposite can go in so many directions.

you know, for instance brother and sister are related and opposite. : )

>Would it not fit better a word that keeps its old appearance when having evolved to a new meaning?

excusing your grammar (per request), I'll again refer you to a current popular form. when you give someone your phone number, it's quite likely to be for your call phone; and if it's not you're likely to say something such as, "that's my land-line".
land-line being the retronym in this case.

aside: the spellchecker here rejects landline in favor of land-line; an example of changing orthography, as landline is preferred to both 'land line' and land-line by many online dictionaries; e.g., wiktionary

-joe (context, context, context) friday