Long story short, they are badly needed. I've been doing work related to crypto these days, and lacking cent/ucent makes everything 10 time worse. I assume DMD already has integral operation legalization for 64 => 32 for plateforms without 64 bits support, so that can be hijacked to legalize 128 => 64. At this point, I don't care if the codegen is crappy. I don't care if VRP and std.math to not work with it. I don't care if half of phobos don't recognize it. I just need to have a 128 bits integers. The last issue about this I could find was from 2012 and it seems like there is no progress made. Please, please, please !
No further progress is expected to be made to support these as a native type - other than possibly as a special enum. Core intrinsics have already been defined for 128-bit integers in core.int128, future direction is going to be moving towards having cent and ucent as a library type. See issue 22827.