With an 801.11ax WLAN, how many simultaneous connections could be made using 160Mhz wide channels?
The question posed is ill defined in some ways. We assume it is referring to one AP (if it is referring to more than one AP, then additional questions arise regarding the layout, etc., and interference between APs comes into the picture).
802.11ax, also known as High Efficiency Wireless, is designed to attack the problem of dense deployment scenarios, i.e., to be more efficient when there are many users attempting to use the same 802.11ax WiFi system. Correspondingly, the target is an increase by a factor of 4, of the average throughput per user in high-density scenarios, such as at train stations, airports and stadiums.
802.11ax is the first family member of 802.11 that supports OFDMA. In earlier generations of Wi-Fi, even up to 802.11ac, channels could not be shared. With 802.11ax, OFDMA is introduced, allowing multiple STAs to share the same 160 MHz channel (or other channel bandwidths also, but since you asked about 160 MHz, that's what we focus on for now). Different sizes may be used for the Resource Units (RUs). The smallest RUs have just 26 subcarriers. In that case, if all STAs are assigned these smallest RUs, a 160 MHz channel can be shared by 74 users. See https://www.ni.com/en-sg/innovations/white-papers/16/introduction-to-802-11ax-high-efficiency-wireless.html for more details.
ps. to be more accurate, there is already some of this kind of simultaneous radio resource sharing in the AP-to-STA direction only even in 802.11ac, but 802.11ax goes further, including support in STA-to-AP as well.