Learn Finnish: Lakimuutos hyväksyttäneen eduskunnassa. - The amendment will probably be approved in the parliament.

Start with the verb hyväksyä (to approve). First, find the passive stem, which is hyväksyttä-. To this, add the potential mood marker -ne-, followed by the passive personal ending -en. This gives us hyväksyttäneen (will probably be approved).

Could I just say Ehkä lakimuutos hyväksytään instead?

Yes, and that is exactly what you would say in everyday spoken Finnish! The potential mood (hyväksyttäneen) is quite formal and is mostly found in written contexts like news articles, official reports, or legal texts to express that an event is highly probable.

Why is lakimuutos in the nominative case here?

Even though the amendment is the object receiving the action (it is the thing being approved), it is the object of a passive verb. A key rule in Finnish grammar is that the object of a passive verb takes the nominative case instead of the genitive-accusative -n.

The base word for parliament is eduskunta. Why does it change to eduskunnassa?

Adding the inessive ending -ssa (in) closes the final syllable of the word. This triggers consonant gradation, causing the strong -nt- in eduskunta to weaken into -nn-, resulting in eduskunnassa.