What happen when transactions are left out from new blocks?

[wingding]

What happen if a miner produce blocks but do not include transactions or only include a fraction of broadcasted transactions?

The reason behind the question is the situation in future where there are no block reward and miners are supposed to be motivated by fees. If many transactions are made without fees, and miners decide to leave them out, they will produce blocks with many tx missing. What happens to those transactions? Are such blocks rejected?

[shorena]

What happen if a miner produce blocks but do not include transactions or only include a fraction of broadcasted transactions?

The other transactions do not get confirmed, but might within the next block mined by someone else or even the same pool.

The reason behind the question is the situation in future where there are no block reward and miners are supposed to be motivated by fees. If many transactions are made without fees, and miners decide to leave them out, they will produce blocks with many tx missing. What happens to those transactions? Are such blocks rejected?

I dont know about the code in >100 years, but the way bitcoin currently works miners can decide which TX to confirm and which not to.

[Pony789]

In fact, many of the blocks have included no transaction other than the coinbase transaction (ie. block reward).
Many of them come from early days when there are very few transactions, and the rest of them include no tx simply because they are found just seconds after the previous block.