This is good news ... I wish they will start production asap ... Canon can count me in as their customer for the EF 28-300 ... it will be incredibly convenient during vacations.
Not if it's the L-version...
There's a non-L 28-300mm from Canon? I haven't seen one... You may be thinking of the old 28-200mm.
FWIW, I use my 28-300
L for travel, and it is very convenient. Is it big and heavy? Yes. But it's no heavier than the two-lens setup it replaces (24-105 + 70-300L), and means no lens changes required.
the 28-135 will finally be replaced ( maybe). I used that lens many years ago...... 
For many years, the 28-135mm was the kit lens for the lower end of the lineup, film cameras, that is. Seems like a refreshed 28-135mm would be a good kit lens for an entry-level FF dSLR...