All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His Slave and Messenger.
The Quran is the word of Allaah, perfectly free from falsehood because it is a revelation from the God who is All-Wise and Praiseworthy. The Quran is a divine book promoting truth and justice. Allaah, The Exalted, says (what means): {And the word of your Lord has been fulfilled in truth and in justice. None can alter His words, and He is the Hearing, the Knowing.} [Quran 6:115] Shaykhul-Islam Ibn Taymiyyah commented on this verse: “'Truth' in what it tells, and 'justice' in what it judges.”
The verse to which you referred in your question was revealed in relation to some of the hypocrites such as ‘Abdullah ibn Ubayy ibn Salool, the chief of the hypocrites. It does not necessarily refer to all the disbelievers. Moreover, even if a disbeliever seems to enjoy worldly pleasures, he may be suffering inwardly because of distress and grief, the gravity of which only Allaah knows. He may also be suffering because of his wealth and offspring; Allaah, The Exalted, says (what means): {So, let not their wealth or their children impress you. Allaah only intends to punish them through them in worldly life and that their souls should depart [at death] while they are disbelievers.} [Quran 9:55]
In addition, not fulfilling a promise is different from not fulfilling a threat; the former is blameworthy while the latter may be praiseworthy. This is, of course, under the assumption that a threat was not fulfilled. Note, however, that the verse may not refer to all of the disbelievers as previously underlined.
You should also know that the Hereafter is the absolute abode of reckoning. In the worldly life, punishment may befall both the believers and the disbelievers. As for the believers, their sins are expiated by means of their suffering and hardships in the worldly life; and as for the disbelievers, affliction in this world is a punishment for their disbelief and transgression. Allaah, The Exalted, says (what means): {… And those who disbelieve do not cease to be struck, for what they have done, by calamity - or it will descend near their home - until there comes the promise of Allaah. Indeed, Allaah does not fail in [His] promise.} [Quran 13:33]
Allaah Knows best.