The title of the meme is an example of what he's thinking about.
"he were" is in the subjunctive mood
"he were better at explaining the subjunctive" is the subordinate clause (it modifies the verb "used to wish" in the main clause)
No matter what verb tense you use in the main clause, e.g., past ("wished" or "used to wish"), present ("wishes"), or future, ("is going to wish" or "will wish"), it wouldn't change the use of the subjunctive mood in the subordinate clause (it would remain "he were" in all cases).