How much do you think a revamped Goodison would make us extra mate - say per annum?
In the short term not a great deal TBH. In the long run;
What i think it would do is completely change the image of the club from skint Everton living on rapidly fading glory to one that's viewed as a forward moving, modern club. Over time the amount we make from sponsorships and what we get out of those relationships would change. Villa got £5m p.a for their kit deal and clubs like Fulham earn more from shirt sponsorship. I don't view either club as more glamourous and neither gets more exposure than us.
I believe it would also change the attitude of our fans and bring a good number back on board as I believe a growing amount are disillusioned with the lack of discernable progress made on or off the pitch. Attendances were down by about 3,500 last season, despite the season following almost an exact same path as the last four or five. Perhaps some of that is down to a recession but I believe it's fans losing patience with the way the club is run.
It also gives room to grow and open new area's to make money. Things like a proper museum(Everton Collection), Weddings, Greater hospitality, Hotels(I wouldn't personally), a health club and on site bars and restaurants all give the opportunity to make money non matchday and increase what we take matchdays.
I believe losing the amount of restricted views would see us go closer to capacity each week too.
If we sucessfully changed the image of the club and managed to get back to a similar level we are at now I would guess that would be worth £12-15m a season for us.