Ah, it does make that part more straightforward. The options become clear:
is
- There is 1 unread topic remaining
- There is 1 new topic remaining
are
- There are 3 unread topics remaining
- There are 3 new topics remaining
- There are [xx] unread topic/s and [xx] new topic/s remaining
There’s a “for you to read” implied there… but when the “or browse” part is attached, strictly read it’s awkward: “[Factual statement], or [action you can do].”
So I was trying to get closer to a set of actions: “Now you can x, or y.”
Hm. If you replace “There is/are” with “See” (& I’d strike “remaining”) then topic/s is the only plural decision to make:
- See 1 unread topic, or browse…
- See 1 new topic, or browse…
- See 3 unread topics, or browse…
- See 3 new topics, or browse…
- See [xx] unread topic/s and [xx] new topic/s, or browse…
(No strong feelings here. I just find this interesting. I’m probably weird.)