As I understand the Irish border problem in Brexit, it is arising because Northern Ireland is deeply divided: one part considers themselves Irish, the other considers themselves British, and neither are willing to give ground. If this answer is to be believed, it doesn't look like anything is going to change soon, which means that no matter what happens in Brexit, the underlying problems are going to remain waiting for the next crisis.
I'm wondering if there've been any concerted attempts to solve this problem by forcing the Catholics and Protestants of Northern Ireland to integrate. This has already been done elsewhere in the world - the example I'm most familiar with is Singapore. This country also experienced similar problems when it was young: it suffered from race-based violence. In view of this the government later set up race-specific policies, such as this one in publicly-managed housing that openly discriminates between races:
The EIP [Ethnic Integration Policy] is put in place to preserve Singapore’s multi-cultural identity and promote racial integration and harmony. It ensures that there is a balanced mix of the various ethnic communities in HDB towns. The EIP limits are set at block/ neighbourhood levels based on the ethnic make-up of Singapore.
For the purchase of an HDB flat, a household with members of different ethnic groups can choose to classify their household ethnicity under the ethnic group of any owner or spouse (co-owner or occupier), according to the race shown on the NRIC of the chosen member.
Once an ethnicity is chosen for the household, it will remain the same when the flat owners subsequently sell their flat on the open market.
A couple of years ago there was also a presidential election which was reserved for a particular racial group.
While it could be argued that these policies are racist, they also achieved their purpose - there doesn't appear to have been race riots for a long time, and Singapore's crime rate is one of the world's lowest, implying there isn't much inter-racial crime either.
Have there been attempts to do something similar in Northern Ireland? Basically, force the two factions to do things like live together, attend the same schools, and view themselves as Northern Irish as opposed to Catholic & Protestant?
It seems this has already been done in the rest of the UK: Scotland for example is made up of lots of clans which had gone to war with each other in the past, yet today they all (?) identify themselves as Scottish and there isn't the same factionalism as in Northern Ireland.