Fight  Loots Will Be Permanent!
In the short term, Zynga is planning to release  some rather nice new  items (Already released) that can only be earned  through PvP (Fighting),  as well as making all Bangkok loot drops  available. In the longer term,  they plan to make the drops more suited  to your level, so that a level  300 player isn't getting brass knuckles  and butterfly knives.
They are  also working on some new systems to  make fighting more interesting  (Fighting Arena). These sort of features  tend to require more time, so  it may be a bit before we can provide  additional details. They are  working on this, however. Plus They're  planning on making some changes  to robbing to reduce the amount of time  after a property finishes before  it is able to be robbed and  increasing the amount of damage you can do  to a property.
They also  have some ideas on how to make fighting more  attractive in Las Vegas,  where banking your money won't be quite so  easy.
Zynga's current  plan is to remove the ability to hitlist a player  unless your health is  above 20. No more phone calls to the heavy hitters  from your hospital  bed.

Improvement of Inventory System
Although this isn't a  short-term project. Zynga is already in the  process of making  improvements to how your inventory is displayed as a  whole, and hope to  provide more details on this in the near future.
How The  Result is Determined for Robbing
Basically,  when you attempt to rob another player, the result is  determined based  on the following:
(Your Attack Skill) + (25% of your Mafia Attack  Strength) + (A Random  Roll based on 75% of your Mafia Attack Strength)
vs
(Defenders  Defense Skill) + (25% of their Mafia Defense Strength) + (A  Random  Roll based on 75% of their Mafia Defense Strength) + (Robbing  Defense  Boosts, if applicable)
As an example, lets say you were trying to  rob someone's Flophouse (each  player brings one extra friend along for  the robbery). Your Attack  skill is 800, and your two best offensive  weapons, armor, vehicles, and  animals add up to a total attack strength  of 600. Your opponent has a  Defense skill of 400; their two best  defensive weapons, armor, vehicles,  and animals combine for a total  defense strength of 600; and they don't  have any Robbing Defense  boosts. You initiate the robbery and the  following numbers are used:
Your  result will be:
A number between 951 and 1400
800 (Your  Attack Skill) + 150 (25% of Mafia Attack Strength) + a random  number  between 1 and 450 (75% of Mafia Attack Strength)
The defenders  result will be:
A number between 551 and 1000
400 (Their  Defense Skill) + 150 (25 of Mafia Defense Strength) + a  random number  between 1 and 450 (75% of Mafia Defense Strength)