Is plastic food packaging completely replaceable?

What did we do before plastic was invented?

Many items were canned, or came in glass bottles. The bottles, of course, required lids. Canned goods became common when Napoleon used them to feed his armies--and they were sealed with soft lead solder, which is a poisonous heavy metal. It is believed with good reason that low grade, chronic and pernicious lead poisoning doomed the Franklin expedition to the Canadian arctic in 1845, and the Seventh Cavalry troops which were wiped out with G. A. Custer in 1876. Lead was not removed from cans in the United States until the 1990s. (Lead is still used in lipsticks.) When people complained about acidic foods in tin cans (such as fruits) and the leaching of tin and lead into the contents of cans, the food industry responded by lining cans with plastic.

Glass containers are often closed with lids containing tin or lead, and often have plastic gaskets so that the metals cannot leach into the contents. Home canned foods (such as we ate when I was a child) are sealed in cans with rubber rings, and can keep for years. (We always wrote the year in which canned foods had been canned, and used them--usually--in date order. When we missed a jar of beans, or tomatoes, or peas or other foods, there was never a problem with the contents, even after as much as five years.

Just as companies with an interest in lead mining encouraged the use of lead in many products, so the petroleum industry has encouraged the use of plastic. It remains popular because it is lighter weight, won't shatter if you drop a jar and can provide conveniences such as squeeze bottles. As Chai has pointed out with her question, foods were long available as canned goods, in tin cans or glass, before plastic was used. It is unlikely to change as long as the appeal of convenience remains a strong motive for buying products packaged in plastic.

EDIT: I'd be interested to know where you read those comments about shelf life--canned goods have been opened that were more than 100 years in the can, and fed to animals without giving them food poisoning. As I've already said, we ate canned vegetables which had been years behind glass without ill effect. Could the articles you read have been published by or refer to research promoted by the petroleum industry?