Intra caste marriage is the very intelligent way of keeping the caste system alive. When we see the history of caste , its because of intra caste marriage only the people in that caste kept among themselves and they never wanted to mingle with other caste people. So they may inhabit the feeling that caste is supreme way to show cast them as them superior then other people in society.
At the same time other than intra caste marriage. There is one more thing which keep the caste system very much alive i.e...Defining caste in terms of occupation. So when you are at one caste, you will be doing only one occupation of your caste to keep up the livelyhood. Because of this you dont find a way to mingle with people in much border way. This create a fear of living i.e when you leave the occupation which your caste is doing, you dont find any other ways to live. Because people from one caste never easily teach the occupation in which they are well versed to the people in other caste. Also people have been branded to do that caste occupation before they born. So this leaves them no option of trying different things.
Here self freedom of choosing our own rights doesnt exist. Now a days this barrier of surviving with the occupation of your caste breaking apart, its a good thing that happens. But it exist in some other way. Still we have been pushed to do things that we wont be willing to do in the name of education and family system.
Family system is another thing which keeps the caste system alive. So Inter caste marriage alone wont be the solution to break caste system. Its a contributor towards the caste free society. Still family, self freedom, work environment all this things have to contribute to break the caste system.