unlockable for engineer speculation

I was wondering what most of you think will be the unlockable for engineer? i think it will be another deployable (force replace the dispenser or sentry or choose which one and include the teleporters.) It might also be a new ranged weapon, maybe repair at a distance.

A laser wrench.

wrench that ratchet has in the ratchet in clank series.

i hope there will not be level 4 sentry!!! its hard to destroy an 3rd level already!!! but that really depends where the engie placed the sentry

Ideas:
1. Engineer can build up an "ubercharge" with his wrench by fixing any building. When the charge is built up his sentry can get double armor / invinciblity
2. Level 3.5 Sentry - optional flamethrower attachment instead of rockets
3. Ability to build mines/surveliance cameras.

2 way teles, although that could prove pretty powerful.

Engineers can drop metal for other engies to build, promoting team work, this may also apply to other classes as amo, we will see.
They may also introduce an alarm that will detect spies within a certain radius of the SG.
Also, one of the classes may be equiped with a laser trip wire. 
All these things have been done before in class based games very similar to TF2.

I would love to see the engineer gain the ability to move a sentry he has built. It would take 3 seconds to pack it up and the time to set it back up would be based on how far he moved it. So if the engie moves his sentry 10 feet it would take 3 seconds to set back up but if he moves it 100 feet it will take 30 seconds to set it back up.

One other thing I have been thinking would be great for the engie is a damage emitter field. It would be a small box the engie would build that would radiate a field of damage so that if a cloaked spy were to pass through it he would become partially visible since he is taking damage.

Untop of an upgrade or new ability what if an engi could call out for other enigs to help him build.  It could work the same way as calling for medic.  Me and my buddy once did this, he builds dispenser and then helps me with sentry gun.  We got a level 3 and level 1 sentry going before the match in dustbowl started and forced the enemy to use the uber right away.  Plus with 2 people repairing a level 3 they only managed to destroy the level 1.  Awsome pwng of noobs when engis team up

here's my idea:
http://www.babble.com/CS/blogs/strollerderby/rosie.jpg