Does Targon's Peak still trigger at the end of turn when the battlefield is replaced with a Brush on Conquer?

Yes, Targon's Peak will still trigger and its effect will resolve at the end of the turn, even if the battlefield is replaced by a Brush token after the conquer occurs.

According to the rules and mechanics of triggered abilities:

1. Triggering: Targon's Peak's ability ("When you conquer here...") triggers at the moment you conquer the battlefield. At this point, the condition is met, and the ability is placed on the chain.
2. Delayed Effect: The ability creates a delayed effect that is scheduled to occur at the end of the turn.
3. Persistence: Once a triggered ability has been placed on the chain or has successfully created a delayed effect, it is independent of the card that generated it. Even if the battlefield (Targon's Peak) is removed, replaced, or destroyed after the trigger has occurred, the delayed effect remains active and will resolve at the end of the turn.

Sequence:

1. You conquer Targon's Peak.
2. The "When you conquer" trigger is placed on the chain.
3. The battlefield is replaced by a Brush token (e.g., via Ivern, Green Father).
4. The trigger resolves, creating the delayed effect for the end of the turn.
5. At the end of the turn, the delayed effect triggers, allowing you to ready up to 2 runes.

This is consistent with how triggered abilities function in Riftbound: once the condition is met and the effect is initiated, it does not require the source card to remain on the board to resolve.