Moving from programming bacteria to programming multicellular system is a giant step. We are already "programming" plants: Genetically Modified Organisms are an example of "programming".
Scientists have been able to program goats to produce a milk containing a protein that is similar (actually better) to the one produced by the silk worm and they now use that milk to create silk that is stronger than the one produced naturally. GMOs based agriculture is widespread, see the map, and it is bound to grow over the next decade under the pressure of producing more crops, which requires not just more effective plants but also plants that can be cultivated in environment that wouldn't be suitable for agriculture.
As human race we made significant progress through the centuries and millennia. Our ancestors thrived in the fertile crescent, because the environment was ideal for agriculture. As time went by crops were slowly changed to fit other ambients and humankind covered the Earth in synch with their capacity to plant, harvest and farm.
The capability of adapting crops and farming animals has increased in these last 100 years, and it is still accelerating.
In the coming decades we will learn to program the "phenotype", that is to engineer plants to obtain what we want in terms of features, like trees producing a better wood for a certain use, plants that can grow with 1/10th of the water they would require today, or at near freezing temperatures....
The jump from programming the genome (to produce a specific protein) to programming the phenotype (to produce a specific behaviour) is a quantum leap. The phenotype is the result of a complex interaction of genes and their expression which in turns is often conditioned by the environment. The level of sophistication is much higher.
We can expect this capability to emerge in the next decade, and to grow in the subsequent ones. This new breed of programmers will be able to highjack a plant code to change it into something that would allow that plant to grow in a completely different ambient or to produce different types of fruits, or wood...
As I discussed in "bacteria programmers" there will be significant ethical issues to be confronted and the range of skills involved will be broad.