Expensive items are a bad idea (over 4k gold)
Especially for pro play. I can already see Caps going Yasuo mid and getting funnelled Jungle gold just so he can get this ridiculous 5k gold item and go around the map 3 shotting Xiaohu's Ryze while twitch chat is like "EU > CHINA POG" and it gives my brain deep pain.
Trinity Force is an item powerspike that a lot of champions rely on, and getting it early or late greatly effects their chances of winning or losing. This is because the item costs so much gold and the passives of the item are so strong. With this new 5k IE, you'd get that effect but far worse. It would be very painful to build, and once it's built, it'll be awful to play against.
ADC's? They won't build the proposed 5k gold IE. They'd get BF Sword and Zeal, deal no damage and barely ever get a crit, have no sustain and just feed, never completing the item.
Also if an item requires you to spend 4k+ gold, it should probably be split into 2 items.
I really hate Phroxzon's "Direction 2". Just my take. You can see this, and other propositions here