|Will I always be able to get support for the open source program I am using now? and where will support come from?|
Similar commercial realities apply to open source support as other software. Just as it can be hard to get support for older DOS and Unix programs today it can be equally hard to get support for say a 15 year old open source project that is now not active. The difference is that as long as someone is technically proficient they can offer support. Unlike closed source software where if the original company is not supporting the product it is very difficult for anyone else to support it if they can not see the code. In addition to this a lot of closed source software is time limited and will not allow you to use the software after a certain period of time.
Support can be offered by many different people and organisations. Often a commercial open source company will offer support directly as one of their value added services and may well have an active partner program full of IT companies who can support the project or an independent IT company can offer support . In some cases it can also be a combination of any of these.