1. Dear Barbar321, you are under no obligation to change your wife's visa from her PBS visa before it expires. Essentially, this visa validates her living and working in the UK until February 2018. In February 2018, as she will have had five years "continuous residence" in the UK she will become eligible to apply for ILR. If she has five years continuous residence before this date, she can also apply for ILR.
2. There should be no obstacle to her obtaining ILR when she has five years continuous residence spent in the UK. Dependents of Tier 2 visas are subject to the normal rules regarding persons granted visas to live and work in the UK. So, once she has been five years continuously in the UK, there is no obstacle to her gaining ILR.
3. Be aware that as you now have ILR, you can apply for UK citizenship after you have had ILR for a period of one year. This will grant you full UK citizenship.
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5. The revoking of the licence of the company who sponsored you is not retroactive in effect. It only operates into the future. Otherwise, all visas issued under the previously valid licence would suddenly become invalid. this is not the case. Al pre-existing visas continue to be valid even if the licence for the sponsoring firm has been revoked. So, your wife's visa is not revoked by the revoking of the licence of the firm who sponsored you. However, if you are concerned, your wife can, today, apply for a visa as the spouse of a settled person, which is now your current status.