Using 'out' as a direction from a central location has been common for a long time, e.g. 'We live five miles out of town'.
In recent years a similar use has been made of 'out' with respect to time, e.g. four year out. "Out' in this case refers to a either four years from now, or four years from a given starting point, or four years until something happens, or four years since something happened, e.g.:
'We are modeling the business environment five years out, so we can prepare appropriate business plans.'
This means we are trying to predict what the business environment will look like five years from now, so we can prepare plans now that will enable us to be ready for those future conditions.
'Cancer patients are considered to be cured if they are disease-free
five years out.
This means that, five years from the time at which a cancer patient goes into remission they are considered to be cured, provided they do not show any signs of cancer during those five years.
'Two years out from the Rio Olympics and we are now anticipating the Tokyo Olympics which are now two years out.
This means that we are two years forward of the Rio Olympics, and two years from now it will be the Tokyo Olympics.
The phrase 'x years out' can be modified using various prepositions, e.g.
'up to x years out', This refers to the period between now and x years from now.
'from x years out', this refers to the period commencing x years from now and extending onwards to an indefinite time, i.e. at least x years.
Addressing each point in your question:
1.Does the phrase in bold mean since 4 years ago or 4 years from now?
As answered above, it basically means from 4 years form now to as far forward as we can reasonably make predictions.
2. Is this informal or idiomatic?
The phrase 'x years out' has found its way into formal business communication. I can't say for sure if it is accepted in academic writing, but I would not be surprised if it was. So it is part way between informal and formal speech. I could not find this use of 'out' in any of the dictionaries that I checked. When this meaning starts to appear in dictionaries, it will have moved closer to being an accepted formal phrase.
In my opinion, I would not call it idiomatic - yet. Although the phase 'x years out' is used among some English speakers, there are many native speakers who would not be familiar with it. So, I suspect that as the phrase becomes wider spread, assuming it will, then it will reach a level of common usage and understanding that would allow it to be called idiomatic.
3. Can "out" be used to talk about the future?
'Out' is always used to talk about the future, but it can be the future measured from a time in the past.
4. I've heard "out" a few times before in talking about time, but never sure if it's about the past or the future. What clues would help me?
'Out' is always talking about a period of time into the future from the given starting time, however, that given starting time could be in the past. Where no given time is provided or implied, the current time can be assumed. 'Out' is never used to talk about a time previous to the given starting time.
We can also talk about being x years out from a future event, e.g. 'In 2022 we will be two years out from the 2020 Tokyo Olympics'. We are counting outwards from the 2020 Olympics, even though it is still a future event today. Similarly you can say, 'In 2017 we will be one year out from the Rio Olympics.' The Rio Olympics is in our past, but 2017 was still in our future in 2016.
5. What if she had used was instead of is? What would have that meant?
As she is talking about at least four years out from the current time, she had to use 'is', 'was' was not a possibility. Four or more years from now, she could look back to today and say, 'Let us look back to what was being planned four years out from then, to see how accurate it was.'
6. Can you give a couple more examples with this phrase?
Dan provides a good example in his comment above.
- There is a website called FiveYearsOut that discusses technology five years from now. NOTE: this site is owned by a commercial organisation
- 'If they are disease-free five years out, the chance of recurrence is extremely thin.' (Washington Post)
- Ten Years Out - A Special Report (Financial Times)
- Customer Experience Predictions: 15 Years Out (Forbes)
NOTE: Be careful, the phrase 'x years out' has other, quite different meanings. The phrase can also used to describe:
The time people have been unemployed, eg 'I am five-years-out and still can't find a job.
The length of time an athlete has been away because of injury.
For example: 'Jones is coming out after 5 weeks out with a groin strain.
'After almost twelve months out of the pool due to disqualification, Jones returned to training last week.