Use of NG & LPG in vehicles

Petrol price hike in Malaysia has encouraged motorist turn to convert their vehicles to use natural gas & LPG, which suppose to be more economical...
Thailand has already been using these vehicles for quite some time.
If we all take a look at the chain and the final consumers. It reveals to us a more threatening situation. What to do when the natural gas & LPG is finished? Or maybe a little better, the price of natural gas & LPG is out of control like the petrol?
There are alternative solutions to curb petrol price hike-drive less, public transports & so on...
There are little solution to curb natural gas & LPG price hike...unless you turn to use electricity to cook...
The fact of high demand=high price is inevitable. When more and more vehicle uses NG or LPG it will create a huge price increase over time.
Should we continue to use NG or LPG in vehicles?Though it seems an economical solution in short & mid term.
Should the Malaysian national car maker look a step further??Since they have already lost in the current competition.