Learn Finnish: He ennustavat, että muuttoliike tulee jatkumaan. - They forecast that migration will continue.

It uses the verb tulla (to come) in the present tense, followed by the main verb in the 3rd infinitive illative form (-maan or -mään). Here, the 3rd person singular tulee pairs with jatkumaan (from jatkua). This construction is primarily used for formal predictions or stating inevitable future events.

Since Finnish usually uses the present tense for the future, could we just say että muuttoliike jatkuu?

Yes, and it would be perfectly correct! However, the tulla tekemään construction heavily emphasizes that this is a definitive future prediction. Because the main verb of the sentence is ennustavat (they forecast), using the analytical future fits the predictive context perfectly.

Why is the 3rd infinitive form jatkumaan instead of jatkamaan?

It comes down to the root verb. Jatkua is an intransitive verb, meaning something continues on its own (like migration here). If a person or entity was actively continuing an action, you would use the transitive verb jatkaa, which would become jatkamaan in this construction.

How is the word muuttoliike constructed?

It is a compound word made of muutto (a move or relocation) and liike (movement, motion, or business). Together, they form the standard term for demographic migration or a migratory movement.