I don't think the general fanbase will be upset since their understanding of the future implications of keeping Miller are probably limited. I am actually in favor of keeping Miller if he would sign a 2 year deal at his current salary with a buy-out/team option on the third. He would keep us competeitive this year, and hey we are 14-5 in our last 19 games I believe, and he, Brand and Iggy could be the lead dogs on some very good teams for the next few years while Thad, Lou and Speights grow into their bodies and abilities. After those two years, unless Miller is still playing at a high level and the team is a contender, you buy him out the same year that WG, Sammy and Reggie come off the books. Maybe you look to move Brand at that time too if needed in something like the JO-Marion trade mode. That summer you have financial flexibility to build around the new, prime time core of Iggy, Thad, Lou and Speights. Hopefully in those two years we have groomed a draft pick to replace Miller. I don't mind that mix of veterans and youth at all.
Miller wanting more than 2 years guaranteed blows that whole idea out of the water since by the time he is gone the financial flexibility would be gone in extensions to Thad and possibly Speights.
I think the general fanbase will be happy if Miller stays because the team will play better this year with him than with any of the replacements I have seen mentioned. If he stays past the deadline, then this summer becomes Stefanski's time of reckoning, he will need to re-sign or replace Miller with limited resources and find a way to make Brand and Sammy fit together this fall. With Brand back there will be high expectations again.