Recent trends in English grammar

Solution 1:

As Barrie mentions, there is little systemic that has changed in English in the last few centuries. Most of the major systemic changes that you might recognise over the last 1000 years, such as the breakdown of the declension system and the simplification of verbal morphology, were probably all but complete by Shakespeare's time or not much thereafter. Some possible candidates of "recent" semi-systemic changes that might sound if not "baffling" at least "very odd" to Shakespearean ears:

• a change in the so-called "raising" behaviour of verbs, so that it is now completely ungrammatical to say "he plays not", and that it sounds much more natural to say "he often plays" rather than "he plays often";
• the frequency with which we now use paraphrases such as "be able to", "have to" etc rather than modals "can", "must" etc;
• there are no new "tenses" as such, but some combinations of elements making up the verb phrase are relative neologisms (e.g. compounds of past passive progressives: "to have been being watched" etc);
• using the 's form with inanimates appears to have been much rarer a century or two ago, so it would probably have sounded very strange to say e.g. "the planet's species", "the book's cover" etc.
• a few other isolated bits of syntax have become more less mainstream whereas they would have been much rarer a couple of centuries ago, e.g. putting elements between "to" and the verb ("to really go", "to fully appreciate", "to not be there"), using analytic comparatives even though synthetic ones exist (e.g. "more cold" instead of "colder").

But on the other hand, these are about as "systemic" as it gets in terms of changes in English over the last few hundred years, and it's probably fair to say that they're not so major as to render the language "baffling" to a speaker either side of the change.

Solution 2:

If the question is about the extent to which earlier generations would be able to understand the way we speak today, I’m not sure it’s one we can ever answer. Its investigation might in any case be better suited to an academic paper than to a place such as this. I would, however, begin by challenging the assumptions on which the question seems to be based. English is marked as much by continuity as by change, and at least two distinguished commentators have drawn attention to the grammatical similarities of the language at different stages of its development. In ‘Think On My Words: Exploring Shakespeare’s Language’, David Crystal writes that

the grammatical rules of English have changed very little over the past 400 years; some 90 per cent of the word-orders and word formations used by Shakespeare are still in use today.

That would apply with much greater force to a period only 150 years ago, so it is doubtful that ‘English of the Victorian times has been significantly more complex than modern day English.’

If we go much further back to the Old English period, the language differs to a far greater extent, partly because Old English was highly inflected. Yet in ‘An Invitation to Old English and Anglo-Saxon England’, Bruce Mitchell writes that

the factor which above all makes Old English seem like a foreign language to those trying to read it today is neither its inflexions nor its word-orders not its syntax, but its vocabulary.