Exegesis:

For amēn ‘truly’ cf. 3.28; ou mē emphatic ‘in no way’ cf. 9.1 (in ch. 13 cf. vv. 2 (twice), 19).

ou mē parelthē hē genea hautē ‘this generation will not in any way pass away,’ i.e. ‘this generation will assuredly be alive.’ This saying is of the same kind as 9.1, and, like that one, nothing is to be inferred here as to when this generation ‘will pass away’: the emphasis here lies on the fact that ‘all these things will happen’ during the lifetime of this generation.

parerchomai (cf. 6.48) ‘pass by,’ ‘pass away’: here in the sense of ‘disappear,’ ‘come to an end.’

hē genea hautē (cf. 8.12) ‘this generation’: the obvious meaning of the words ‘this generation’ is the people contemporary with Jesus. Nothing can be gained by trying to take the word in any sense other than its normal one: in Mark (elsewhere in 8.12; 9.19) the word always has this meaning (cf. Lagrange).

mechris hou (only here in Mark) ‘until,’ ‘until which time’: a succinct way of saying mechris ekeinou tou chronou en hō ‘until that time in which.’

tauta panta ‘all these things’: in the context this can only refer to all the events described in the discourse. (Notice that tauta ‘these things’ of v. 29, and tauta panta ‘all these things’ of v. 30, correspond to the tauta and tauta … panta of the disciples’ question in v. 4.)

Translation:

For truly employed in this type of construction and for generation see 8.12. By far the most common translation of generation in this passage is ‘those living now’ or ‘people who are now alive.’

Pass away cannot be translated literally in most languages. The closest equivalent is generally ‘die,’ but if a term parallel to the use of pass away in the following verse can be employed, this should be done.

Take place is translatable as ‘occur,’ ‘happen,’ or ‘become’ (Greek genetai), often in the future tense or its equivalent, since these events followed the statement of Jesus.

Quoted with permission from Bratcher, Robert G. and Nida, Eugene A. A Handbook on the Gospel of Mark. (UBS Handbook Series). New York: UBS, 1961. For this and other handbooks for translators see here .