IPv6 vs IPv4 available subnets - enough or too less

Solution 1:

If your address plan could use more, ask your LIR or ISP, they can accommodate you. Possibly reach 64 thousand /64s is an indication you could more comfortably use a larger prefix. Plan for the future.

One subnet is one size fits all, a /64. Not reserving 64 bits for the host part will break things, and is not necessary.

End users need multiple /64s. Everyone does, a corporate campus plus regional offices, small business, or home user. RIRs will recommend to keep it simple, with a /48 per site or customer. ARIN bumps your assignment up to the next hex digit (/44, /40) well in advance by it being strictly necessary based on numbers of /48s.

Site is not well defined, but could be any organizational unit that could use 4 hex digits of address space to play in.

Consider that Hurricane Electric's 6in4 tunnel service assigns a /48 for free. IANA has only started on a fraction of the available address space, and there already is enough for every person on the planet to have thousands of /48s.