I know what you’re talking about but your interpretation (assuming you don’t mean it tongue in cheek), is in my opinion anachronistic.
You’re right that originally the form “thou” was the equivalent of the “singular you” in other languages while “you” was both for addressing more than one person and for speaking formally / reverentially to someone, thus the equivalent of the “plural you” in many modern languages. During the 17th century, more and more people started addressing everyone with “you” (the common interpretation is that with the rise of the middle classes and with the movement of more people into cities, people were afraid of offending a stranger who might be their social equal or superior, and so used “you” just to be safe. Thus it may be correct to say that, from the 17th to the 18th century, the custom of addressing everyone using the plural arose. It is also correct to say that the English “you” operates in accordance with a plural grammatical structure.
However, that is no longer how the average English native speaker perceives the word “you”. People perceive it as a universal singular and plural form today. This is also evidenced by the fact that 1) we often need to use more complex forms to signify a plural form of second-person address (you all, y’all, you people, you guys) and that in fact some dialects have come up with new vernacular plurals (youse, yinz).
Also, modern English lacks the strictly coded greetings that often go with the plural / singular you in other languages. When we greet someone, we can say “Hi” / “Hello” and “Good bye” / “Bye”, and a bunch of other things and no one will really care, no matter who we’re addressing (yes, there are more formal forms like “Dear Mr. / Ms.”, but they’re used a lot less than before and certainly not every time we address an elder, boss, etc.) Whereas for example in Czech, it’s very important to use the right greeting when addressing someone (Czech etiquette is derived from Austro-Hungarian etiquette, which places the kind of importance on greetings that Anglo-Saxon etiquette places on saying “please” and making requests politely). If you are speaking to a person to whom you are supposed to speak using the plural “vy”, practically the only polite way to say Hello is “Dobrý den” (Good day – you may slur it to “Dobrej”). Using the friendly form “ahoj” or “nazdar”, or even the neither here-nor-there form “zdravím” (I greet) is considered insolent (how dare he think we’re familiar / friends!!!) There are also equivalent formal and informal good-bye forms. Modern English lacks that. No one will be particularly horrified if, on a typical North American city street, one man addresses another with “Hey, buddy!”
Thus I would argue that in English, “you” has undergone a semantic shift and is no longer a universal formal plural but a neutral universal singular and plural.