There would be ways to achieve real security
For example you could have an enhanced type systems where every variable can contain complex types. Types like "this is an integer containing a prime number", or "this is a block of data which must not leave the scope of this function". With such features you could comfortably write and proof the correctness of your code automatically. Research in that area is on its way. If we'd spend as much effort researching this as we spend managing virus scanner licenses, we could make substantial progress.
You could go further and have tagged memory, where variables contain their type in memory and the hardware can check for illegal operations like multiplying a string and an integer, or sending a data-block which has a "must not leave system" flag to the network card.
The proposed system probably won't bring any security. People who know about security will be able to make secure systems without it. It's little use storing your key on a separate little system, if the attacker simply calls the same function as your insecure PHP webshop does.
It's also little use allowing only signed code to boot as it's extremely unlikely someone will sneak into the secure data center and covertly replace the boot sector.
Maybe a tiny little example of how a strongly typed system can prevent errors:
WHILE length(s)<5 DO s:='0'+s;
Now if x could be negative, you'd get a string like 000-3. However the type "word" implies that this is an unsigned and always positive integer. If you try to call the function with a negative value, you will either get a compiler error or an exception. Now contrast that with C where types are just syntactical sugar and not enforced. What happens if you do a malloc(20+x) and x is -30? How can you keep an attacker from giving you unsuitable input without having to resort to manually checking everything? If you could just say, x is an integer between 2 and 500, your compiler could put in the necessary code for you at the best possible position. And as a side effect it can even optimize the code better.