What I wear now is exactly the kind of clothes that most under 60s wear, I shop in the same shops as DD and DDiL, and, even, DGD. I see no reason to wear any particular style just because I am now in my 70s. If I like the look of myself in something I wear it. DD would be quick enough to warn me off if I was unsuitably dressed.
I think the biggest danger to older women is the tendency to not change their style once they reach their late 40s. I was that age in the 1980s. The number of my friends and acquaintances around my age who still like floral mid length skirts with a smart jacket over is too many to count. I stopped wearing them aorund 1989.