That hubset is designed for Uniglide, Hyperglide and Hyperglide compatible cassettes including SRAM. The only compatibility issues are with some outer cogs.
The threaded outer Uniglide cog for the 1978-1984 Dura-Ace EX will not work because it used a smaller pitch diameter in order to allow cogs down to 11T. All spined Uniglide cogs will work. All other threaded outer Uniglide cogs will work.
The 11T Hyperglide cogs also have issues with this freehub. Due to the smaller diameter of the 11T cog, it has a reinforcing flange that prevents the cog from from fully seating on a standard Hyperglide freehub. It is intended for a Hyperglide -C(ompact) freehub with the outer edge of splines being relieved. Still, an 11T Hyperglide cog will work on standard Hyperglide freehub like yours but the entire cassette will sit slightly farther out and require a spacer behind the large cog. This shift may cause clearance issues with the frame stays.
There's no reason to use Uniglide if your freehub is Hyperglide compatible. Hyperglide, provides better shifting, particularly under heavy load and has wider availability, with better ratio selection.
Regarding the future availability of 8 speed Hyperglide cassettes, I don't see them being discontinued in the near future. As of 2019, Shimano still offers 8 speed on their Claris group in several popular ratios (12-25T, 13-26T, 11-28T, 11-30T, 11-32T and 11-34T). Shimano typically continues to offer replacement parts support for consumables like cassettes, for several years after they have been discontinued as an OEM item.