Learn Icelandic: Að öðru óbreyttu verður þessari ráðstöfun haldið áfram. - Other things being equal, this measure will be continued.

This uses the pattern of að + dative pronoun + dative adjective/participle. öðru is the neuter dative of annar (other), and óbreyttu is the neuter dative of óbreyttur (unchanged). Literally meaning 'at other unchanged', it is the standard Icelandic way to say 'all else being equal'.

Why is þessari ráðstöfun in the dative case here?

Because the phrasal verb halda áfram (to continue) requires its object to be in the dative case. Even though this sentence is in the passive voice, the noun retains the dative case that the verb originally assigns to it.

If ráðstöfun is a feminine noun, why is the past participle haldið in the neuter singular form?

This is a standard rule of the Icelandic passive voice: when a verb governs the dative or genitive case, its passive participle does not agree with the noun. Instead, the participle stays frozen in the default neuter singular form (haldið).

Why does the sentence use verður instead of er to form the passive?

Using verður (from the verb verða) puts the passive voice into the future tense. While er haldið áfram means 'is being continued' right now, verður haldið áfram translates to the future 'will be continued'.