Additional alternate recipes for high level items, which can be assigned to constructors and only have one item-type as input and no output. High consumption rate of 60 per minute would be good. Those recipes can be used as intermediary resource sinks for players who wants them for their factory-complexes until something better comes along.
Currently there is no automatic way to destroy items besides manually dragging stacks onto the Trash-icon by hand. (EDIT: Some) People want sinks for items they no longer want, which disappear without manual interaction. Some people just build mega-storage areas (EDIT: with hundreds of storage containers) but it's not the best idea performance wise and it's not really needed gameplay-wise to have multiple thousand stacks of items laying around somewhere and every storage will be full at some point. (EDIT: Some people seem to be offended by that.)
Every expansion of the factory and optimization of power supply and resources and production comes to a sudden hold when the storages are full and manually deleting hundreds of stacks is no fun at all. Now with the introduction of trains, this becomes even more a topic because they allow large quantities of stacks moved around.
Now it would be nice, if we had a more elaborate resource sink, e.g. the Space Elevator, which automatically and continously want items, for example the items of the highest tier unlocked or something (and we could see the nice Elevator animation more often). But for the time being that's not available.
Another device / building to consume any items which is send to them would also be nice, but someone must model it first and it must be programmed and tested and so on and I guess there are currently more important things to do for the developers.
So why not add alternate recipes to the game, which just consumes one type of high-end product but don't deliver anything for them. Than players could build constructors to destroy specific items with belts. Of course a dedicate device to destroy stuff might be better, but I guess adding some small alternate recipe is super easy to accomplish in minutes and can seamlessly integrated into an ongoing patch and removed if something else can be delivered. And would make a lot of people happy with this and may give them a reason to play again for while and a reason to expand the production and try to optimize the flow of items.