In short: Samsung seems to be working on a wireless DeX solution although there is no clear indication of when a wireless version will become available. The information on this has come from a moderator on the European Samsung forums who confirmed (via SamMobile) as much by stating the company is "working on a wireless connection for DeX."
Background: Samsung's DeX feature allows users of compatible devices to engage with a desktop-like experience by connecting the device to PC-like peripherals. This is a new feature compared to others, although it did first debut in early 2017 on the Samsung Galaxy S8 and S8 Plus. However, the implementation in use at that time was fairly rudimentary as it required substantial hardware to bridge the gap between the phone and the additional hardware. It's this that has over the time been refined with the hardware going through phases that on each case becomes smaller and less intrusive. For example, the most recent version of DeX comes on the Galaxy Note 9 and can be used just by connecting the phone to a display with a cable. Therefore, it would stand to reason that a future version of the same technology would be a cable-free version. Which is what seems to be the case with Samsung now understood to be working on that exact implementation.
Impact: Needless to say, the immediate impact of a wireless version of DeX would be an increased ability for users to make use of the feature without having to rely on any additional components, including cables. This will not only increase the appeal of the feature at the functional level, but also on a financial note, as the user presumably would not need to invest in any other equipment. This in itself would likely increase the number of people who would be more inclined to use the feature in the first place. It does need to be pointed out that moderators in communities and forums are not always the most reliable sources of information, and so while it's the case that a semi-official confirmation has now come through, that's not to say Samsung is definitely working on a wireless DeX option. Or, that it will definitely arrive to market soon as wireless solutions tend to be more prone to issues than wired, and the same moderator did make it clear that a "few improvements" were still needed.