The tzaddik who never bows

ומרדכי לא יכרע לשון עתיד לרמוז כי לעולם בכל דור נמצא בכלל ישראל איש צדיק שהוא לא יכרע.

"And Mordechai would not bow" — the future tense is used to hint that always, in every generation, there is found within Klal Yisrael a tzaddik who will not bow.

The Sefas Emes reads the verb "yichra" (will bow) in its future form as a hint: in every era there arises a tzaddik who refuses to bow to falsehood and keeps the connection to Hashem alive for all of Bnei Yisrael.

וזה שכתוב ויבז בעיניו לשלוח יד במרדכי לבדו כי הגידו לו כו' עם מרדכי.

And this is what is written: "It was contemptible in his eyes to lay a hand on Mordechai alone, for they had told him… the people of Mordechai."

Haman understood that striking down Mordechai by himself would accomplish nothing, because the matter was bound up with "the people of Mordechai" — the whole nation that Mordechai represented.

פירוש כי הבין כי מרדכי יצא מן הכלל ללמד על הכלל כולו.

The meaning is that he understood that Mordechai had emerged from the collective in order to teach about the entire collective.

Mordechai was not merely an individual; he was a representative who reveals the inner strength latent in all of Bnei Yisrael.

ואפילו אם ימית את מרדכי. יהי' אחר במקומו בכח כלל יהודי.

And even if he were to kill Mordechai, another would arise in his place by the power of the collective Jewish people.

Because the refusal to bow flows from the strength of Klal Yisrael as a whole, killing one tzaddik cannot end it — another will inevitably take his place.

ולכן רצה לאבד כל עם מרדכי:

Therefore he wished to destroy the entire people of Mordechai.

Realizing the source lay in the nation itself, Haman sought to annihilate all of Bnei Yisrael, hoping to uproot the very wellspring from which such tzaddikim arise.

Summary: The future tense "Mordechai would not bow" teaches that in every generation a tzaddik stands firm by the power of all of Bnei Yisrael; Haman grasped this and therefore sought to destroy the entire nation, not Mordechai alone.