For $F to stop selling trucks in North America would be financial suicide. They sell on average an F series every 30 seconds. F series numbers for 2018 are trending up, with this March being the largest March month they've had in five years[1]. Not to mention, trucks are really expensive. A nice loaded F-150 can easily cost $40k and above.
[1] http://fordauthority.com/fmc/ford-motor-company-sales-number...