Please....when I got married my initials became PMS.
I ordered a backpack from LLBean and the lady offered me monogramming. I said no and she told me it was free because I had an LLBean Visa. I said no because my initials weren't so good. She said "Oh come on...how bad could they be?". I said "My monogram would be PMS. There was a pregnant pause and she finally said "Oh my, how unfortunate".
Needless to say, I got no monogram.
That's hilarious! But I probably would have gotten the monogram...I love it! 
"Even I get" that it's probably still on "the books" as the most formal form of address, but it is, in this day and age, archaic. And I was referring to my MIL addressing birthday cards and a magazine subscription to me, not Charles inviting me to William's wedding. Any formal invitation that I might receive most likely would include my DH, and as I DID make a less than enthusiastic decision, of my own choosing for my own reasons, to take his last name, they WOULD be addressed to Mr and Mrs John Smith. However, to address me ALONE as Mrs John Smith in every day life (cards, magazine subscriptions) is rarely used these days, is certainly NOT acceptable to me, and even etiquette experts, last I looked, "get it" about having entered the 21 century and therefore, the practice IS archaic, and Mrs Mary Smith is perfectly acceptable and as formally acceptable as the archaic "Mrs John Smith". If you choose to respond to an invitation addressed to "Mrs John Smith", go for it. I can't even begin to imagine receiving one addressed as such, but I'd have to judge the invitation in its entirety (from whom, to what, my desire to attend) before deciding how to respond, if at all.
Too funny! (Well, too "something".) What other people do with their relationships is that fearful to you and your marriage? Wow. With all the gay marriages that have taken place, and with all the people choosing different approaches to their names after marriage, not once did I ever feel afraid of any of it.
Just have to say you have a very progressive system there
...
I will say, though, that our different names led to some annoyance with Disney. After booking our last vacation online and getting something in the mail addressed to "The MyLastName Family," I called to make a change and also asked them to please note that we'd prefer to be "The HisLastName Family." I was told they'd add a note about it. We continued to get "MyLastName" things in the mail, though, even though each time I had to call for something (it was a complicated multi-family trip, and I wound up spending a LOT of time listening to Disney hold music
) I guess I don't understand where if you're keeping your name for feminist reasons, why you would find it acceptable for the children to be given the male parent's name by default.
I have absolutely no issue with married people having different last names (most of my friends do), but I find it strange that their children almost always have the husband's last name. Whatever the wife's reasoning for keeping her maiden name, it's as if it's automatically assumed that the kids will have the father's name. (I know one family where the children have the mother's name and people act as though it's some atrocious act that indicates what a horrible/crazy/selfish person she is.
He is fine to do so if he so desires. Heck, I could care less if they both take a brand new name. The norm is for the woman to take the man's name. One benefit of doing it this way instead of your proposed way is that it eliminates future confusion.
