Conditional relative clauses that vividly anticipate the realization of a future event take the subjunctive with ἄν. The main clause has the future indicative or any other form referring to the future.
τῷ ἀνδρὶ δν ἂν (= ἐά_ν τινα)
ἂν οἱ ἄλλοι ἐργάζωνται, τούτοις σὺ χρήσῃ
πειρά_σομαι ὅ τι ἂν δύνωμαι ὑ_μᾶς ἀγαθὸν ποιεῖν
ὅποι ἂν ἔλθω, λέγοντος ἐμοῦ ἀκροά_σονται οἱ νέοι
ἀπόκρι_ναι ὅ τι ἄν δε ἐρωτῶ
ἕπεσθε ὅπῃ ἄν τις ἡγῆται
ὥστ' ἀποφύγοις ἂν ἥντιν' ἂν βούλῃ δίκην
a. The future indicative is scarcely ever used in a conditional relative clause of this sort (
b. Homer has some cases of the subjunctive without κέ or ἄν (e.g. N cross234). Homer sometimes uses the future with κέ or ἄν in the main clause: ὁ δέ κεν κεχολώσεται, ὅν κεν ἵκωμαι
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].