The phrase "would merely be" is correct and can be used in written English.
For example, you could say: "The task at hand would merely be to complete the report by the end of the week."
Glencore would merely be the latest in a long line.
Our universe would merely be one of them.
That would merely be to repeat the mistakes of 1996.
If God had a commonplace proper name, He would merely be distinguished from other deities.
The addition of Anthony would merely be enhancing an existing strength, not addressing a weakness.
Previously applicants would merely be informed by letter whether or not they had been successful.
Which would merely be funny if it weren't also proving true on occasion.
In more sedate countries, such systems failures would merely be embarrassing.
The fear is he would merely be considered another yes-man.
Ironically, the hedge funds themselves would merely be inconvenienced by over-regulation.
If Obama were to show up at the end it would merely be symbolic anyway.
