The best choice is to stick to the agreement that London won't prefer any party of NI... so, end the coalition
The electoral arithmetic provides no other credible alternative. At the moment we have:
Con + DUP v Lab + LibDem + SNP + PC + Green
Con + LibDem would work, so arguably avoiding NI involvement is up to LibDem. For that matter so would Con + SNP. In Italy we've seen the Northern League transform themselves from a separatist party to a whole-Italy political party, so in theory it could be done. However no solution is something that the government can themselves manage. There would have to be an initiative from LibDem or SNP.
The idea of DUP joining the opposition parties in six-party coalition against the Conservatives is a non-starter. A six-party coalition would be unworkable. Additionally the DUP have religious objections to the sympathies of Corbyn and could not possibly work with Labour under the leadership of an IRA supporter. Remember, Corbyn was actually arrested for his support of an IRA terrorist.
A new election needs three changes:
1) We have to get rid of the constituencies which are now close to a gerrymander. These should have been changed in the late 1990s. There has been delay after delay. The changes should go through in autumn this year.
2) We have to get rid of massive voter fraud. We need voters to show ID to vote. We need much stiffer penalties for political parties that promote double voting (ie Labour, who have a convicted election fraudster on their team).
3) We have to resolve the issue of Putin's interference. This has to be done by government IT specialists as a matter of national security, but right now the systems are not in place.
The seat loss to the Conservatives of each of these is significant:
1) Probably 15-20 seats - this is a major issue.
2) Hard to measure. SDLP and LibDem are almost certainly victims in 2017 (London/Derry and St Andrews seats). The Conservatives may have lost in the region of 10 seats.
3) Make up your own figure! There are suggestions of 20-80 out in the shady parts of the internet.
Once these changes are made I think an election becomes sensible.
Bradley is of course the NI secretary. I had forgotten she had already replaced Brokenshire, so no further changes.