"The World to Come" in the context of Hebrews is the Millennial Kingdom of Jesus Christ. I think this comment in The Grace New Testament Commentary is good: 2:5. In vv 5–9 the author reflects on God’s original plan for man, namely, for him to have dominion over His entire created order (cf. Gen 1:26–28). Though the fall of man (Genesis 3) undermined that plan, God will yet fulfill this future kingdom, which the author designates as the world to come. The Greek term for world (oikoumenē) is used in Ps 93:1 and 96:10 in the context of the Lord’s eschatological reign. This kingdom was not given to angels but to the Son to reign over (as further proof of His superiority). This kingdom is the same as that already introduced in chap. 1 (e.g., 1:8) in fulfillment of the Davidic Covenant promise of an eternal throne and kingdom (1:5). Tanner, J. P. (2010). The Epistle to the Hebrews. In R. N. Wilkin (Ed.), The Grace New Testament Commentary (p. 1038). Denton, TX: Grace Evangelical Society. Also, this comment on Heb 1:14 is relevant. 1:14. In contrast to the Son ruling at God’s right hand, the angels are ministering spirits. Unlike the Son whose destiny is King over an eternal throne-kingdom, the role of the angels is to minister, not reign. In fact, they minister to those who will inherit salvation. By salvation, our author is thinking not of our Lord’s saving work on the Cross, but a future salvation associated with His Second Coming (emphasized in chap. 1). This is quite clear in light of his use of “salvation” in 9:28, as well as his explicit mention in 2:5 of “the world to come.” Although there is a salvation for believers to inherit, this can be jeopardized by their neglect (2:3). Thus before p 1037 continuing the author will pause in 2:1–4 to warn his readers. Tanner, J. P. (2010). The Epistle to the Hebrews. In R. N. Wilkin (Ed.), The Grace New Testament Commentary (pp. 1036–1037). Denton, TX: Grace Evangelical Society.