I'm waiting for Bluetooth 5 to be used on a wireless headset
You shouldn't. It won't make a huge difference and you won't hear any difference on most material, such as lossy streaming.
Sony's proprietary LDAC already has higher specs than Bluetooth 5.0, with lossless transmission of 24-bit / 96 kHz using some clever packing / unpacking of the data over the BT 3.0+ wireless pipe.
I've been using LDAC for over a year now and can confirm that it's capable of delivering greater detail on some material, such as SACD rips (hi-res FLACS and DSD) but it's usually only audible on certain spots of certain tracks.
For some context, I can easily tell between AptX and SBC in a blind test. However, once you get to beyond AptX (such as LDAC, AptX HD or BT 5.0) the improvements are marginal, and good luck with being able to tell any difference at all on highly compressed modern recordings. Unless you predominantly listen to well-mastered, high dynamic range acoustic recordings such as classiclal or jazz, or some digitally remastered older analog recordings, you'll get very little benefit from hi-res capable headphones.
Post Bluetooth 3.0 with AptX, the drivers and the active electronics of a given pair of bluetooth headphones make a far greater difference to the sound quality than any tweaks to the transmission protocols.
Bluetooth headphones will keep getting better every year and my prediction is that 2017 will see the biggest growth in this market to date (thanks to Apple in no small part), which should result in higher investment in R&D by the manufacturers; however, BT 5.0 will play a far greater role as a marketing tool than as a driver (no pun intended) for any real improvement in the fidelity of bluetooth headphones.