Speaker upgrade
New speakers will definately be an upgrade from the Bose. On that narrow wall you wont get good imaging and surround sound from 3 speakers mounted right next to each other.
I would recommend two bookshelf speakers on stands or wall mounts on each side of the TV and a center channel mounted above the TV.
Also clarify whether your budget is for 5.0 speakers, 5.1, 7.1, etc.