ULSD fuel isn't going to render the old equipment obsolete.  I'd even
venture out as far to say that it'll be beneficial.

to quote the energy.gov website

"Older vehicles can also burn ULSD. While older vehicles will achieve a 10
percent decrease in soot emissions by burning ULSD, the new vehicles
designed for ULSD will achieve emissions reductions of up to 95 percent"

it's not much different then when eastern states started banning methyl
bromide in gasoline.