One of the problems is that Shapechange has a Concentration requirement, and at that tier, anything worth grappling is going to be hitting you hard while you are doing it.
Ooh, that is an excellent point. I'd planned on taking both Resilient Con and Warcaster in the build, but you're right, even that may not be enough for the kind of hits I'll be taking. Warding bond may be a good Magical Secrets pick to cut those con check DCs.
But maybe Bladesinger (with a Rogue 1 dip for expertise) would be a better route? Gets an additional +4 to con checks (assuming a headband of intellect, since I'll be using ASIs for feats instead of Int boosts), and can reduce incoming damage via Song of Defense for easier con check DCs. No magical secrets, but a much better base spell list, so I figure that's a wash. I know it'll be a weaker grappler until those high levels, but I think I can live with that... just play it as a standard wizard/bladesinger until then.