The canon seems to indicate that not only “COULD” he be that he “SHOULD” be.
How often are people excommunicated?
[How often are people excommunicated?]
They will ultimately be held accountable.
Can 1364 §1 says: Without prejudice to the prescript of can. 194, §1, n. 2, an apostate from the faith, a heretic, or a schismatic incurs a latae sententiae excommunication
Latae Sententiae means that it is automatic: in other words, as soon as he became a heretic, he was excommunicated -- no trial is needed.
But there are times where a bishop will make a declaration of excommunication -- confirming that something that happened automatically has, in fact, happened. For example, when Bishop Paprocki made a declaration of excommunication for Mary F. Keldermans (for participating in a "woman ordination"). But such a thing is the exception rather than the rule.
Don’t forget Sotomayor!