Um.
The Germans had ballistic V2 missiles; think Scud missile launchers, not computerized, low-flying, terrain-following missiles.
Shields... Shields might be a step too far. Major buildings, military fortresses - maybe. Maybe.
Pretty reasonable, although I have my own ideas on what that will be. Here are a few please feel free to add your own -
Horizontally Mounted Engines - A fundamental reordering of the BattleMech's interior on par with the Torso Mounted Cockpit was considered possible but unwarranted by designers whose maintenance and cost issues would be much more than normal.
Dual Fusion Engines - Building on the Horizontal Mounts this innovation allows BattleMechs to utilize two Engines each spaced out over the torsos working as one. Two 200 Fusion Engines would equal a 400 and of course would need a four ton gyro in order to balance things out. [Granted this is far off and needs work]
Enhanced Pulse Lasers - somehow improve the ranges on InnerSphere models
Large, Medium, and Small Flamers - building on the original model I'd like to scale these up
Engines - interior reorganizations don't change much. Dual engines? I have dual-engine small craft I use in the bomber, Cap-missile torpedo bombers, or space-superiority craft. To keep the munchie-factor to a minimum I ruled they need to be standard engines.
Lasers - how about a blend of pulse and heavy laser tech? Extra range from the sheer strength of the beam, extra damage from the pulse, more heat from the heavy laser tech
Flamers - I guess. Maybe limit the range along with the mass? Range 1/2/3. Mass .5, 1, 2. Damage might be heat for Mechs, damage for other vees and infantry, or whatever rule you prefer.
Why not make a coherent list of desired new tech, first, then we can all debate it?