Currently there are 3 bills before the US House of Representatives, and 1 before the US Senate, to establish a National Concealed Carry Reciprocity covering legal carry od guns nation wide, The basis is this. If you have a concealed carry permit issued by your home state it would be good in all states that require a concealed carry permit. If a state has a concealed carry permit law, they must recognize your out of state permit. That would mean that states like MD, PA, Etc. would have to let DE. permit holders carry in their state. If a state does not allow a conceal carry in their state, they would not be forced to let people carry. Then there are some states that allow concealed carry without a permit.
This would not change the responsibility of the carrier in these states. You would be responsible for knowing and following the specific laws of that state you were in.
The following are the bills I speak of:
SB. 498
HR. 402
HR. 923
HR. 986
All bills and their Co-Sponsors are available on-line.