On my touring bike I have a 48-36-26 with a 10 speed 11-32 in the rear (or a 11-36 which I have in my garage in case I want to do a sailboat towing race uphill).
There's a couple of reasons not to do what you propose, one of which is the same reason why I switched from 11-36 to 11-32 in the rear on it - gear spacing. With an enormous dinnerplate cassette in the rear, the jumps between cogs are big enough that it's bothersome. The other reason is that, for the most part, it's simply not necessary, because most hills in most places where people choose to ride just aren't steep enough that a typical road double with a 11-28 or 11-30 in the rear is going to run out of gears. If you never ride double digit climbs then you're just hauling unecessary weight. Mechanically, big differences between chainrings and a big cassette would require a honking big rear derailleur and chain to actually work well.
Of course, there are times when a triple is brilliant - going up a hill which goes well into the double digits knowing you have the gearing to simply sit and spin a comfortable cadence without getting out of the saddle, struggling with traction, tacking and whatnot is quite simply brilliant.
I just don't see the bike industry moving in that direction - on the road I'd predict that they'll increase the gearing range by going 12 speed with smaller chainrings in front and something like 10-30 cassettes in rear. Economically it makes more sense for them to ditch the triples to streamline production and inventory.