How many simultaneous threads will your next computer be able to run?
Chances are it already runs at least two, most probably four. It's not unreasonable to see 4 and 8-threads as the norm. Also keep in mind we are only considering x86s. SPARCs, IIRC, can do up to 64 on a single socket. ARM-based servers should follow a similar path.
BTW, a fully-comfigured MacPro does 12. A single-socket i7 machine can do 12. I never saw a dual-socket i7, but I have no reason to believe it's impossible.
There are dual-socket and even quad-socket 8-core hyperthreaded xeons (the Xeon L75xx series). A 1U Intel with 64 threads will set you back about $20k.
AMD has 12-core chips, so you can get 48 cores in 4 sockets there. (But I think they only have one thread per core)
Chances are it already runs at least two, most probably four. It's not unreasonable to see 4 and 8-threads as the norm. Also keep in mind we are only considering x86s. SPARCs, IIRC, can do up to 64 on a single socket. ARM-based servers should follow a similar path.
BTW, a fully-comfigured MacPro does 12. A single-socket i7 machine can do 12. I never saw a dual-socket i7, but I have no reason to believe it's impossible.
Considering that, -j64 seems quite reasonable.