This passage is for the Narrative Lectionary for March 13, 2016 (along with Mark 13:1-8)
It is also for Revised Common Lectionary for Advent 1, Year B, most recently Dec 3, 2017
Summary: Check your 2nd coming baggage at the ticket counter and preach the text!
For those preaching on those during Advent: This passage is a great passage for a culture swamped with Christmas chores. Our focus should not be on to-do lists that come and go, but on Jesus Christ and his Word!
Otherwise: I also think you can play around with the word authority and derive the mission of the church from Mark's Gospel: While we await the coming of Christ in an age of idolatry masked as piety, we are to pray and teach prayer; cast out unclean spirits and heal people; we are to spread the Good News of repentance and forgiveness.
γρηγορειτε ("watch out". 13:34, 35 and 37) This word comes into English as "Gregory". To note: in the very next chapter the disciples will not be able to stay awake...
θλιψις ("suffering", "distress" or "tribulation"; 13:24 and also 13:19) This is hard word to translate. "Suffering" has all sorts of baggage, both in the Bible and in our culture. "Tribulation" can mean a particular thing to certain people. As Wikipedia helpfully summaries:
In the futurist view of Christian eschatology, the Tribulation is a relatively short period of time where anyone who chose not to follow God before the Rapture and was left behind (according to Pre-Tribulation doctrine, not Mid- or Post-Tribulation teaching) will experience worldwide hardships, disasters, famine, war, pain, and suffering, which will wipe out more than 75% of all life on the earth before the Second Coming takes place.
I would translate it "distress" here. But I want to focus on why. Normally I believe in "canonical" translation, that is, help people see connections within the larger context of Scripture. However, suffering and tribulation are such buzzwords that they distract from the immediate point of Jesus: There will be an age of false messiahs and prophets who will claim to be saviors. The great distress is living in an age where people turn away from the true worship to idolatry, the worst kind, where people call it Jesus but it is not.
Power: There are three different words in this passage that relate to power.
αι δυναμεις (25): When this word (coming directly into English as "dynamite") is in the plural, it means miracles or deeds of power. In this case, it is translated "the powers," a logical translation, but strange use of the word!
δυναμεως (26): Here the word is an adverb meaning powerfully
εξουσιαν (34): Here the word means authority. The man in the passage has conferred authority on his people. It is worth noting that in spite of the fact that the end is coming, Jesus has still given us authority to do works. In chapter 6 of Mark's Gospel, Jesus gives his disciples authority. In that case, they were called to cast out unclean spirits, heal, evangelize and preach repentance. In chapter 11 you might also argue that Jesus gives his disciples authority to pray, to teach and to forgive. If you put these together, you come up with the mission of the church in Mark's Gospel:
While we await the coming of Christ in an age of idolatry masked as piety, we are to pray and teach prayer; cast out unclean spirits and heal people; we are to spread the Good News of repentance and forgiveness.
Grammar note one: Why learning future participles is a waste of time
The construction of 13.25 is so odd. The word for 'fall' here (from pimp-oo; πιμπω) is a present tense participle used with the a "to be" verb in the future tense. This construction (instead of a future participle) is a good lesson of why you should not waste any time learning future participles. They are so rare and even Greek speakers avoided them with other constructions, using the familiar English construction of: "They will be falling"
Grammar note two: Strong future denials
In 13.31 the promise of Jesus that his Words will never pass away is a ου μη construction, ie, a STRONG future denial. Also interesting is that this word (parercho-mai; παρερχομαι) appears in 2 Cor 5:17, Behold, Everything has passed away. This could effectively be translated, "no way, never gonna happen."