I bought an -06 not too long ago...decided it paired well with my 7.5x55 Swiss and has an outstanding blend of performance. I can buy M1 spec ammo for easy shooting, and generally pretty decent accuracy, for little money. I can also buy ammo that'll flatten anything from vermin to moose/elk/what-have-you. That rifle is off getting a Bartlein CFW installed and will likely land in a McMillan stock (to compliment its factory Maple) eventually. If you pushed me to keep only one bolt gun, it would probably be that one.
OP, if you're basing your concern about the potential of 30-06 slipping away into antiquity, followed by extinction because of what you see here on Rokslide, you're missing the mark. The collective mindset one might observe on Rokslide is but a sliver of the overall rifle hunting world, and those who would be shopping for a general big game hunting rifle. The majority of hunters have no idea what Rokslide is.
I haven’t found many cartridges that do anything much better then a ‘06 and nothing that does so much so efficiently. I’ve killed nearly everything Alberta has to offer with mine shooting everything from 130 grain Barnes at nearly 3400 FPS to 200 grain accubonds at 2730 FPS. I’ve shot 170” white tails, 190” mulies and 350” elk with a 165 accubond at 3,000 FPS too. The old war horse gets it done every year and if I had to go down to one centerfire rifle it would be a 30-06.
Now I don’t play at 400+ yards because I still know how to stalk into sensible range. Ballistic coefficients aren’t my primary concern so the 6.5’s and .284’s don’t interest me. Those two calibers and their associated cartridges give up efficiency due to the diameter of their bore. The projectiles are slippery but to get the velocity you need more case capacity or pressure.
My shoulder isn’t made of glass but burning another 20 grains of powder for a 150 FPS increase doesn’t excite me either so .30 cal mags are out. I’ve got a .338 for the hunts I want more penetration but they’re few and far between.
To suggest she’s grown irrelevant only highlights your ignorance. That cartridge has nearly achieved perfection with modern bullets and powders and will likely live as long as civilians own rifles.