It is mostly a shorthand for the type of ingredient in a sandwich. So you have veggies, sauces, (vegan) cheese, and of course bread. The actual macronutrient profile is likely to be more varied than just protein, like with a legume patty.
My diet does tend to be fairly low in protein, from what my food logging has shown. I am going to start some strength training and regular exercise within the next few weeks, so I want to have a balanced diet there.
This is so hard to answer because so many of these things you don't miss it until it's gone. I'm going to say physical keyboards. Like, not that physical keyboards will disappear entirely, but I think they will continue to get much, much less common. I think a lot of people will miss the tactile advantage of a good keyboard, though.
One thing I think we're in for a rebound on is how we deal with batteries. Currently, the paradigm for many devices is that manufacturers put a rechargeable battery in and that's it. When the battery wears down or breaks, the device is done too. This can't go on forever. It's creating too much e-waste, expense, and pollution.
I think the deal that customers are getting from streaming services is probably too good to last, in general. It's already starting to degrade, with companies all going to start their own streaming platforms with smaller and smaller catalogs. You have to really plan for what you want to see. The rise of exclusive shows really damaged things. Vertical integration like that hurts competition.