Windows on ARM has had a shaky start and struggled to gain traction, but with the new Microsoft Surface Pro X with the new SQ1 processor co-engineered with Qualcomm, things are starting to look rosier.
It is claimed that x86-64 emulation will be arriving shortly allowing 64-bit programs to be compatible with Windows on Arm, but this could come at a cost.
Qualcomm's Miguel Nunes claimed back in 2016 that x86-64 software emulation wasn't going to happen. The reason behind this is that due to the RISC architecture 64-bit computing is far slower than 32-bit computing. With x86-64 emulation, everything the software does is CPU bound with no GPU interaction, this, therefore, puts a great deal of strain on the CPU and causing performance issues.
So with the x86-64 support, you will have a wider range of access to applications but this will come at a cost of reduced performance. This doesn't mean Windows on Arm laptops will reduce in overall performance, they will continue to favour 32-bit.
32-bit emulation currently uses Windows' WOW64 which enables 32-bit programs within 64-bit Windows. Microsoft and Qualcomm are working to enable 64-bit compatibility across a wide range of processors going back to the Qualcomm Snapdragon 835, therefore extending compatibility from 64-bit exclusive processors such as the Qualcomm Snapdragon 8cx.
I previously reviewed the HP Envy X2 and had some mixed experiences with it at first with various software issues, but I have continued to use it over the years and all of these issues have been ironed out. It is not something I used every day, but if you want a portable always-connected device they are excellent. I was and still am excited about Windows on Arm, however, I had hoped they would have come further by now with the performance and emulation issues.