IDA Pro disassembler fully supports 16Bit DOS executables (they only removed the support from the recent free versions - thats why most using IDA Pro Free 5.0)

IDA Pro disassembler fully supports 16Bit DOS executables (they only removed the support from the recent free versions - thats why most using IDA Pro Free 5.0) but Hexrays the decompiler does sadly not support 16bit code (intentionaly) but i think the Hexrays guys could do wonders here (in comparison what Ghidra is able to do)