will future battle fields require the use of heavily armed tanks or more deployable, faster, and cheaper units?

I think both of them got an even share on the proportion.
If we are to put too much concentration on the armor rather than speed, the vehicle will become :
1) Too heavy thus the deployment will become difficult. Most of the roads and bridges were not design to support a fully armored vehicle. Remember that most of the roads and bridges were design to support a civilian vehicle not military.
2) The vehicle will become too slow and unmanuvarable thus become vulnerable for enemy ambush. The vehicle will also become too slow to keep up with another faster unit in the field of battle.
3) The vehicle will consume a much more fuel than ever before. This will make the cost of the maintennance much expensive than it should be.
4) The heavy armor and excelent fire power will do more than just a threat for the enemy.
A good example of this kind in the past is The King Tiger Tank. It is the most powerfull tank during the WW2 but profen to be more of a burden for the Fuhrer's wehrmarcht, althought it's deployment in the field were fatal for the Allied and Russian ground forces.
If we are to put too much concentration to the speed, than the vehicle will be :
1) Fast enough to become a good recon unit, but not much for a head to head encounter or to spearhead a military operations.
2) The light weighted vehicle will virtually hold no protection against enemy fire and can easily be destroyed by the enemy.
3) The vehicle hold no strength it needs to hold the battle line during an engagement. It will also hold no firepower which is very important for any armed forces across the globe.
An example for this kind in the past can be seen the Russian BT tank. This vehicle is a race horse for the Russian ground forces during the WW2. It's thin armor and lack of fire power were useless when encountering the NAZI's military might. But it's dazzling speed, make it fast enough to avoid enemy fire and to be sent as fast as posible to the front line. Not forgetting to mention, it's small and compact body is easy to hide in the field. It's cheap prize during production was also something to be add. The Russian built thousand of this thing which making it an even balance of force against the NAZI's panzer division. In the field it is often that a single panzerIV will go up against 4-5 of this BT tank.
For overall, the design for the future battlefield vehicle would be much reflecting itself to the succesive design in the past, especially the ones during the several major conflict such as, the WW2, the Vietnam Conflict, and the Gulf War.

i THINK THAT THEY BOTH HAVE A EVEN SHARE WE REALLY NEED BOTH OF THEM TO WORK. PRETTY MUCH WE NEED BOTH OF THEM FOR IT TO WORK

Tank Supply Policy
Under the above heading, Winston Churchill wrote a 6-point memo dated 23rd April 1943. Written as a result of receiving positive reports on "his" tank, it was addressed to Sir Edward Bridges et al.

"The idea of having a spear-point or battering ram of heavily armoured vehicles to break the enemy's front and make a hole through which the lighter vehicles can be pushed has a very high military significance."

Successful when followed in WW II - probably would be just as effective today.

blitzkrieg

I think there should be and even amount of both because to little or to much could prove fatal to the crew and infantry depending of it.

If it's not armored heavely enough it it would be faster, but it would also be useless in head-to-head tank combat.

If it's too heavely armored it would be easier for opposing tanks to hit because of it's decreased speed.

In essence, the question boils down to tradeoffs, and the arms race between armor and anti-armor technology. Frankly, I would prefer speed and mobility over firepower, but in reality, a mix of both power projection and mobility will be the best mix. If you look at some of the experiences from Iraq, the mix of the M1 Abrams and M2 Bradley when deployed as fire teams is a good example of the kind of balance I'm talking about to handle the maximum variation of situations.

This is a century old dilema. The solution can't be found in current technologies because of the inherent limitations of tracked and wheeled chassis systems. Undoubtably they have specific proven capabilities,that will always remain valid,but extracting much more performance out of these is getting more difficult. It requires a complete departure from any existing vehicle,including the engine. So,regardless of sophisticated high tech add-ons,all chassis are based on a few century old technologies. The Future Combat System remains a target because it is a lumbering dinosaur.