Some information then came alight from a reliable source, @mattchw1, who released an image of an upcoming Hot Wheels x Transformers Optimus Prime. It appears to be a G1 Optimus Prime truck which will be released under the Hot Wheels Truck Fleet collection. According to a listing via Toywiz website it will be priced $7.99 and ready to ship in August this year.
Update: It now appears Mattel will indeed proceed with the RLC version of this truck on 21 May. More information at https://hwth.net/forum/red-line-club...-optimus-prime and Hot Wheels Optimus Prime | Mattel Creations