Cameron stated that negotiations with EU would be postponed till October when a new PM is elected.
The negotiations will take about 2 years.
According to EU constitution a member state can exit on condition that 75% of all member states agree to it.
Conclusion: No Brexit will take place. It has been a fraud to imitate democracy.
No, once the UK formally signifies exit, then under Article 50 of the Lisbon Treaty it will happen in two years time unless the UK and the EU jointly agree to delay the exit. However, that would be a bald exit with nothing done to smooth the exit. It's the withdrawal agreement that is intended to make the exit less painful that requires negotiation that requires a qualified majority (19 of the remaining 27 comprising 65% of the remaining population) of the EU to agree.
It might be possible, depending on the scope of what can be included in the withdrawal agreement, to have Scotland join/remain in the EU while bypassing the threat of a Spanish veto under article 49 on an independent Scotland joining the EU. Similarly, perhaps NI and Gibraltar's continuing membership in the EU could be negotiated. After all, it's only England and Wales that wanted out, and there already is precedent for only part of a member state to be in the EU.
I just got an idea, what if instead of invoking Article 50, the UK government seeks to have England and Wales listed in Annex II as a non-European country or territory?