I think what they have in the 2 current boxed sets is fine. 2 Mechs in the "starter" and 8 in the "full rules" is great.
For everyone that says they don't need Tanks/PBI, I would simply say, we had this thing back in the day called "CITYTECH" and I think most people loved it.
My point is that I'm fine w/ adding in Tanks/PBI, but it should be as an Expansion, not as a next edition of AGoAC.
I could also see a clan boxed set too. Though clan unit sizes makes for a hard to match size issue.
For a new "Cititech" I would go with 4 or 8 mechs, and then add in 8 tanks & some Infantry counters. Allowing you to be the same size or a bit larger in scope as AGoAC is.
For the Clan pack.... I'm torn between 5 Mechs, 10 Mech, or 8 mechs+elementals.
I think make the ideal might be 5 Omnis, 3-5 Second Line mechs, and then 5 Elemental Points allowing you to form 2 "lances" (mixed stars) of Mechs & BA.
As for what mechs to choose from........
"Citytech" = Wasp, Stinger, Marauder, Warhammer for sure as base 4..... plus...... Phoenix Hawk, Crusader, ShadowHawk, & Rifleman if its an 8 mech set.
Then add in 2 each, Manticore, Patton, Pegasus, & Maxim + 4 infantry stands/platoons (2 foot, 1 jump, 1 motorized)
"Clan Box"..... MistLynx, Horned Owl, Viper, Conjurer, Stormcrow, Timberwolf, Galahad, Gargoyle + 5 Elemental Points.
IDK, I feel like those keep the boxes decent sized, a bit larger than AGoAC even, so the price point won't go up much.
I also really like the idea about adding in some scenarios. Even if its just a single page printed out.
Heck, you don't even have to make them new. Pull something from the old scenario books with the little sidebars of fluff & mechs/maps/rules in the middle of the page.
I think if the "CityTech" box as I'm calling it was based some historic battle in the 4th SW or Wo39 & you had a bit of fluff about that war in there w/ the scenario you'd be good to go.
Duplicate the same thing w/ the Clan Box & pull out some Twycross/Tukayid/Luthien battle fluff.
You wouldn't need quite as much "fluff" books as the last boxed sets but some maps & maybe a short story for that era that is already from battlecorps?
Small rulebook covering the new tech/units found inside.
Actually, if they don't have new versions of the Unseen for a full 8 mechs then possibly going with the extra 4 as units coming from the Sabers/FoxTeeth books & showcase 39 tech with the Austin/Daniel/Grace/etc etc variants might be nice.