These are not two additional Pencil models as some people here seem to be thinking for some reason. The article states that they are updated models of the two existing models--Pro and USBC.
There's also no indication that these new models won't be backward compatible. As a reminder or FYI to those who don't know, the reasons for the lack of backward compatibility with older iPads in the current/previous Pencils were not arbitrary. They were necessary due to circumstances at the time, directly or indirectly due to changes in hardware which benefited most customers (or at least most vocal customers). Those changes were the switch from Lightning to USBC, from port charging to magnetic charging, and from portrait camera to landscape camera.
Right now the Pencil is a simple two-model lineup (Apple still sells older Pencils only because people still have older iPads, but they will be phased out), and with these updates it will continue as a simple two-model lineup in order to accommodate customers with different needs and looking for different price categories, just like there are different iPhone tiers. And note that the only incompatibility to be aware of in current lineups is the Pencil Pro and the base iPad. Those cannot be compatible without adding hardware and cost to the base iPad.