The street topic is an old discussion, I suppose - practicality vs. visuals. We'll certainly also discuss this topic again for our next project (as we have done also for Anno 1800) but there are also good reasons for keeping this system. We'll see.
On the other two topics: Both Crown Falls (Sunken Treasure) and Manola (New World Rising) offer significantly more building space than your average island, if this is something you prefer. However, ultimately, islands and the logistics tying everything together, are a core part of the Anno games and we don't think that getting rid of this would be a good idea. There might be smaller islands, there might be bigger ones, but having only one large landmass to build on is, in our eyes, not compatible with the "Anno DNA".